add tests for deploy

[jla-gardner]

Adds tests to ensure that all models can be "deployed" (i.e. compiled to torchscript and saved to disk), re-loaded and used.

These tests highlighted bugs, including:

• torchscript's inability to handle non-standard ascii characters (such as Φ and Δ - 😢)
• not all models outputting local energies of shape (n_atoms, )

[codecov]

Codecov Report

Attention: Patch coverage is 96.55172% with 1 line in your changes missing coverage. Please review.

Project coverage is 87.25%. Comparing base (d85cf6c) to head (6bfc529).

Files	Patch %	Lines
src/graph_pes/deploy.py	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #7      +/-   ##
==========================================
+ Coverage   85.04%   87.25%   +2.21%     
==========================================
  Files          32       33       +1     
  Lines        1805     1914     +109     
==========================================
+ Hits         1535     1670     +135     
+ Misses        270      244      -26     

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