CI: Update .flake8 configuration and fix flake8 errors in lib/init/grass.py

[arohanajit]

Description

This pull request addresses several Flake8 warnings and improves exception handling in the GRASS GIS initialization script. The changes focus on removing unused variables and replacing bare except clauses with more specific exception handling.

Changes

1. Removed unused 'e' variables in exception handling for locale errors.
2. Improved exception handling when reading the VERSIONNUMBER file.

Specific Changes

1. Removed unused 'e' variables:

In the locale setting section, removed as e from two except locale.Error clauses where the error variable was not being used.

# Before
except locale.Error as e:
    # code not using 'e'

# After
except locale.Error:
    # code remains the same

[echoix]

Just fine tune the title and it looks fine enough to merge!

The changes are quite simple and limited in scope.

[echoix]

@arohanajit Would you fix the conflicts so it can be finished ? (A merged PR from this morning removed an exclusion line just besides the one that this PR removes, so it ends up conflicting)