Fix test upstream: -y to pip uninstall

[sneakers-the-rat]

We have a pileup of related PRs:

• Fix hidden windows failures #360 - currently failing because of this, needs to be merged ASAP
• Ensure that relative imports can be imported without requiring ./ in front of the import file name #350 - fails on windows, masked by 360
• Specify repo and branch when testing against upstream #367 - includes this, but does more
• Poetry 2 upgrade (PEP612-conformity) and gh-actions renovation #364 - also touches this action orthogonally (and removes the need for this) but needs changes in upstream

Trying to break the backlog with this tiny little commit that should let us do 360, which then will let us handle the rest

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.38%. Comparing base (1b5e9f7) to head (f4a9311).
Report is 22 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #369      +/-   ##
==========================================
- Coverage   63.43%   63.38%   -0.06%     
==========================================
  Files          63       63              
  Lines        8982     8980       -2     
  Branches     2574     2572       -2     
==========================================
- Hits         5698     5692       -6     
- Misses       2665     2669       +4     
  Partials      619      619              

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[amc-corey-cox]

This seems quite straightforward to me. I'm approving.