updated pytim requirements

[Marcello-Sega]

The latest version (1.0.2) adds compatibility with numpy2 and MDA 2.8, but requires now python>3.1 and mdanalysis >=2.8.0

[Marcello-Sega]

The test environment behave strangelyl; It reports this errror:

=================================== FAILURES ===================================
______________ [doctest] pytim.observables.local_frame.Curvature _______________
168 
169         Example:
170 
171         >>> import MDAnalysis as mda
172         >>> import pytim
173         >>> from pytim.datafiles import WATER_GRO
174         >>> import numpy as np
175         >>> g=mda.Universe(WATER_GRO).select_atoms('name OW')
176         >>> inter = pytim.ITIM(g,molecular=False)
177         >>> curv = pytim.observables.Curvature().compute(g)
Expected nothing
Got:
    Warning: without having a PYTIM interface or passing
    a refgroup, the surface normal will be meaningless

while the actual docstring is different:

"""
       >>> import MDAnalysis as mda
        >>> import pytim
        >>> from pytim.datafiles import WATER_GRO
        >>> import numpy as np
        >>> g=mda.Universe(WATER_GRO).select_atoms('name OW')
        >>> inter = pytim.ITIM(g,molecular=False)
        >>> curv = pytim.observables.Curvature().compute(g)
        >>> print(np.array_str((curv[:10,0]),precision=2,suppress_small=True))
        [-0.04 -0.17 -0.44 -0.15 -0.31  0.06  0.08 -0.22  0.08 -0.27]

"""

I added conda to my CI, and it passes with flying colors.

@IAlibay, could you help me having a look at this when/if you have time?