fix: remove texture guessing for vispy, try texture_format='auto' before falling back

[tlambert03]

This removes the "look before you leap" logic for creating an openGL context and checking whether float textures are supported before using texture_format='auto' on vispy. Instead, it just tries to use 'auto' and falls back to CPU-backed textures if it fails.

The reason is that some tests have been failing periodically for wxPython (emitting a warning from the CPUScaled texture). Looking into those test errors made me realize that wx was never using GPU scaled textures on vispy, and that was presumably due to an error in the output supports_float_textures in a wx context. Rather than try to fix that, it think it's better to just try to use a gpu-texture, and let vispy error and fallback to CPU

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.49%. Comparing base (c1be08a) to head (76b26e6).
Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #98      +/-   ##
==========================================
- Coverage   71.71%   71.49%   -0.23%     
==========================================
  Files          43       42       -1     
  Lines        4430     4406      -24     
==========================================
- Hits         3177     3150      -27     
- Misses       1253     1256       +3     

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