replace deprecated argparse.FileType, fixes #9266

[ThomasWaldmann]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.57%. Comparing base (4eed3ec) to head (3630eaa).
⚠️ Report is 6 commits behind head on 1.4-maint.

Additional details and impacted files

@@              Coverage Diff              @@
##           1.4-maint    #9267      +/-   ##
=============================================
- Coverage      80.59%   80.57%   -0.02%     
=============================================
  Files             38       38              
  Lines          11256    11256              
  Branches        1771     1771              
=============================================
- Hits            9072     9070       -2     
- Misses          1615     1616       +1     
- Partials         569      570       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[github-actions]

Backport failed for master, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin master
git worktree add -d .worktree/backport-9267-to-master origin/master
cd .worktree/backport-9267-to-master
git switch --create backport-9267-to-master
git cherry-pick -x 3630eaafdff8d34cbabec833a8067e1f29162040