Fix error from type annotations containing ellipsis

[jayqi]

Fix runtime AttributeError for type annotations with ellipsis literal (e.g., tuple[int, ...]).

Closes #124.

[github-actions]

🚀 Deployed on https://deploy-preview-127--nervous-visvesvaraya-4b7042.netlify.app

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.4%. Comparing base (e77348e) to head (0b334a2).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #127   +/-   ##
=====================================
  Coverage   98.4%   98.4%           
=====================================
  Files         19      19           
  Lines        819     821    +2     
=====================================
+ Hits         806     808    +2     
  Misses        13      13           

Files with missing lines	Coverage Δ
erdantic/core.py	97.6% <100.0%> (+<0.1%)	⬆️