Cannot write LASFile which contains datetime64[ns] objects

[kinverarity1]

Describe the bug
A LASFile object containing a curve of dtype datetime64[ns] cannot be written to a LAS file unless converted to strings.

To Reproduce
See failure for case #2 below:

from datetime import datetime
import lasio
import numpy as np
import traceback
import sys

dt_data_original = np.array([
    datetime(2021, 9, 29, 12, 0, 0), 
    datetime(2021, 9, 29, 12, 0, 1), 
    datetime(2021, 9, 29, 12, 0, 2)
], dtype=datetime)
dt_data_1 = dt_data_original
dt_data_2 = pd.Series(dt_data_original)
dt_data_3 = dt_data_2.astype(str)

for i, dt_data in enumerate([dt_data_1, dt_data_2, dt_data_3]):
    las = lasio.LASFile()
    las.add_curve("depth", data=[1, 2, 3])
    las.add_curve("datetimes", data=dt_data)
    las.add_curve("data", data=[10, 7, 12])

    print(f"=============\nCase #{i + 1}\n=============")
    print(type(dt_data))
    print(dt_data.dtype)
    print("\n")

    try:
        las.write(sys.stdout)
    except TypeError:
        print(traceback.format_exc())

=============
Case #1
=============
<class 'numpy.ndarray'>
object


~Version ---------------------------------------------------
VERS.   2.0 : CWLS log ASCII Standard -VERSION 2.0
WRAP.    NO : One line per depth step
DLM . SPACE : Column Data Section Delimiter
~Well ------------------------------------------------------
STRT.m 1.00000 : START DEPTH
STOP.m 3.00000 : STOP DEPTH
STEP.m 1.00000 : STEP
NULL. -9999.25 : NULL VALUE
COMP.          : COMPANY
WELL.          : WELL
FLD .          : FIELD
LOC .          : LOCATION
PROV.          : PROVINCE
CNTY.          : COUNTY
STAT.          : STATE
CTRY.          : COUNTRY
SRVC.          : SERVICE COMPANY
DATE.          : DATE
UWI .          : UNIQUE WELL ID
API .          : API NUMBER
~Curve Information -----------------------------------------
depth    .m  : 
datetimes.   : 
data     .   : 
~Params ----------------------------------------------------
~Other -----------------------------------------------------
~ASCII -----------------------------------------------------
    1.00000 2021-09-29 12:00:00   10.00000
    2.00000 2021-09-29 12:00:01    7.00000
    3.00000 2021-09-29 12:00:02   12.00000
=============
Case #2
=============
<class 'pandas.core.series.Series'>
datetime64[ns]


~Version ---------------------------------------------------
VERS.   2.0 : CWLS log ASCII Standard -VERSION 2.0
WRAP.    NO : One line per depth step
DLM . SPACE : Column Data Section Delimiter
~Well ------------------------------------------------------
STRT.m 1.00000 : START DEPTH
STOP.m 3.00000 : STOP DEPTH
STEP.m 1.00000 : STEP
NULL. -9999.25 : NULL VALUE
COMP.          : COMPANY
WELL.          : WELL
FLD .          : FIELD
LOC .          : LOCATION
PROV.          : PROVINCE
CNTY.          : COUNTY
STAT.          : STATE
CTRY.          : COUNTRY
SRVC.          : SERVICE COMPANY
DATE.          : DATE
UWI .          : UNIQUE WELL ID
API .          : API NUMBER
~Curve Information -----------------------------------------
depth    .m  : 
datetimes.   : 
data     .   : 
~Params ----------------------------------------------------
~Other -----------------------------------------------------
Traceback (most recent call last):
  File "<ipython-input-90-52992b419c0b>", line 28, in <module>
    las.write(sys.stdout)
  File "c:\devapps\kinverarity\projects\lasio\lasio\las.py", line 523, in write
    writer.write(self, file_ref, **kwargs)
  File "c:\devapps\kinverarity\projects\lasio\lasio\writer.py", line 213, in write
    data_arr = las.data
  File "c:\devapps\kinverarity\projects\lasio\lasio\las.py", line 823, in data
    return np.vstack([c.data for c in self.curves]).T
  File "<__array_function__ internals>", line 5, in vstack
  File "C:\ProgramData\miniconda3\envs\wrap\lib\site-packages\numpy\core\shape_base.py", line 283, in vstack
    return _nx.concatenate(arrs, 0)
  File "<__array_function__ internals>", line 5, in concatenate
TypeError: The DTypes <class 'numpy.dtype[datetime64]'> and <class 'numpy.dtype[int32]'> do not have a common DType. For example they cannot be stored in a single array unless the dtype is `object`.

=============
Case #3
=============
<class 'pandas.core.series.Series'>
object


~Version ---------------------------------------------------
VERS.   2.0 : CWLS log ASCII Standard -VERSION 2.0
WRAP.    NO : One line per depth step
DLM . SPACE : Column Data Section Delimiter
~Well ------------------------------------------------------
STRT.m 1.00000 : START DEPTH
STOP.m 3.00000 : STOP DEPTH
STEP.m 1.00000 : STEP
NULL. -9999.25 : NULL VALUE
COMP.          : COMPANY
WELL.          : WELL
FLD .          : FIELD
LOC .          : LOCATION
PROV.          : PROVINCE
CNTY.          : COUNTY
STAT.          : STATE
CTRY.          : COUNTRY
SRVC.          : SERVICE COMPANY
DATE.          : DATE
UWI .          : UNIQUE WELL ID
API .          : API NUMBER
~Curve Information -----------------------------------------
depth    .m  : 
datetimes.   : 
data     .   : 
~Params ----------------------------------------------------
~Other -----------------------------------------------------
~ASCII -----------------------------------------------------
    1.00000 2021-09-29 12:00:00   10.00000
    2.00000 2021-09-29 12:00:01    7.00000
    3.00000 2021-09-29 12:00:02   12.00000

Expected behavior
There shouldn't be an error. Obviously the writer code needs significant re-factoring, but in the meantime this is an unpleasant bug.

Software versions (please complete the following information):

• Python version: [e.g. 3.6 32 bit]
• Python distribution [e.g. Anaconda]
• lasio version (import lasio; print(lasio.__version__)) : latest (0.30.dev74+g85bf606)

Additional context
Add any other context about the problem here.

[kinverarity1]

Of course.... even cases 1 and 2 are problematic because they will read back in incorrectly given they contain whitespace 😞