Improve the TensorNet model class coverage

[kenko911]

Summary

A unit test is added for testing SO(3) equivariance to improve the coverage.

Checklist

• Google format doc strings added. Check with ruff.
• Type annotations included. Check with mypy.
• Tests added for new features/fixes.
• If applicable, new classes/functions/modules have duecredit @due.dcite decorators to reference relevant papers by DOI (example)

Tip: Install pre-commit hooks to auto-check types and linting before every commit:

pip install -U pre-commit
pre-commit install

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.29%. Comparing base (c612f62) to head (93574e0).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #276   +/-   ##
=======================================
  Coverage   98.29%   98.29%           
=======================================
  Files          35       35           
  Lines        3117     3117           
=======================================
  Hits         3064     3064           
  Misses         53       53           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.