FIX: Throw value error for unsupported version of Mechanical

[dipinknair]

Fixed #913

if no version is provided to App() takes the latest Mechanical version found in system and throws warning.
In case of Linux, mechanical-env ensures only one version (either from saved path or latest version found in default installations directory) is found when checking AWP_ROOT env.

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 14 lines in your changes missing coverage. Please review.

Project coverage is 80.95%. Comparing base (f51a086) to head (8e687e2).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #917      +/-   ##
==========================================
- Coverage   85.30%   80.95%   -4.36%     
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  Files          35       35              
  Lines        2226     2232       +6     
==========================================
- Hits         1899     1807      -92     
- Misses        327      425      +98