add version check for mpl

[akaszynski]

With

from matplotlib import colormaps, colors

In pyvista/plotting/colors.py if matplotlib<3.5.0 we get an ImportError. Since we don't specify a minimum version for matplotlib since it's not a direct dependency, and neither does vtk, we can either try to make our imports backwards compatible or just complain about a minimum supported version.

Since 3.5.0 was out around a year ago, I think it's safe to simply require it, even though it seems a little restrictive. We can implement a follow-up PR with some additional logic if we deem it necessary. For now, this is a improvement over the current implementation.

[codecov]

Codecov Report

Merging #3583 (8d209b6) into main (b99e5f8) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #3583   +/-   ##
=======================================
  Coverage   95.17%   95.17%           
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  Files          83       83           
  Lines       18571    18572    +1     
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+ Hits        17675    17676    +1     
  Misses        896      896