fix(python): output a warning for .venv activation errors

[mwbrooks]

Changelog

Output a warning instead of an error when activating the Python virtual environment (.venv/) fails.

Summary

This pull request updates the Python virtual environment (.venv/) activation issues to be output as warnings.

Related to feedback: #347 (comment)

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 65.08%. Comparing base (c449532) to head (ad9bc9e).

Files with missing lines	Patch %	Lines
internal/shared/clients.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #368      +/-   ##
==========================================
+ Coverage   65.06%   65.08%   +0.01%     
==========================================
  Files         215      215              
  Lines       18179    18179              
==========================================
+ Hits        11829    11832       +3     
- Misses       5254     5255       +1     
+ Partials     1096     1092       -4     

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