feat: timestamp & date enhancements

[aceforeverd]

• fix timestamp or date type as go query parameters.
• basic facility to support SQL Null as input or output.
• more tests

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 74.35897% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 65.10%. Comparing base (49f51dd) to head (bffc68a).

❗ Current head bffc68a differs from pull request most recent head 8155c14. Consider uploading reports for the commit 8155c14 to get more accurate results

Files	Patch %	Lines
conn.go	71.42%	5 Missing and 1 partial ⚠️
encode.go	60.00%	1 Missing and 1 partial ⚠️
types.go	84.61%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #8      +/-   ##
==========================================
+ Coverage   57.75%   65.10%   +7.35%     
==========================================
  Files           3        4       +1     
  Lines         187      192       +5     
==========================================
+ Hits          108      125      +17     
+ Misses         61       49      -12     
  Partials       18       18              

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