Make sure to instantiate str variable before adding to it

[CasperWA]

Fixes #322

AI Summary

This pull request includes updates to the .pre-commit-config.yaml file and improvements to error handling in the setver.py script.

Configuration updates:

• .pre-commit-config.yaml: Removed a comment about the latest version for Python 3.8 for the pyupgrade repository.

Error handling improvements:

• ci_cd/tasks/setver.py: Enhanced the error message construction by initializing the msg variable as an empty string and appending additional information conditionally.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.37%. Comparing base (5aac677) to head (3f03dbd).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #323      +/-   ##
==========================================
+ Coverage   84.61%   85.37%   +0.76%     
==========================================
  Files          12       12              
  Lines         936      937       +1     
==========================================
+ Hits          792      800       +8     
+ Misses        144      137       -7     

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