feat: add ansys-mechanical-stubs as a dependency

[klmcadams]

Add ansys-mechanical-stubs as a dependency to pymechanical. Use from __future__ import annotations to make all type hints strings and prevent Model's type hint from failing

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.96%. Comparing base (baaa546) to head (117f9f1).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #948      +/-   ##
==========================================
+ Coverage   80.94%   80.96%   +0.01%     
==========================================
  Files          36       36              
  Lines        2278     2280       +2     
==========================================
+ Hits         1844     1846       +2     
  Misses        434      434