CI: add back weekly bot to update uv lockfile

[github-actions]

Using CPython 3.10.12 interpreter at: /usr/bin/python3
Resolved 138 packages in 1.67s
Updated xdsl v0.25.0+47.g46c79300 -> v0+untagged.1.g2a38956

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.74%. Comparing base (0e1cec0) to head (29e4a79).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3641      +/-   ##
==========================================
- Coverage   90.75%   90.74%   -0.01%     
==========================================
  Files         467      467              
  Lines       59138    59138              
  Branches     5661     5661              
==========================================
- Hits        53668    53666       -2     
- Misses       4022     4023       +1     
- Partials     1448     1449       +1     

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[superlopuh]

I'll try to repurpose this action to instead trigger on dependabot updates