feat!: remove deprecated backup window flag

[phm07]

This flag has been deprecated (and not working) since 2018: #147

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.14%. Comparing base (f2fb321) to head (2bddf46).
⚠️ Report is 485 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #710 +/- ##
==========================================
- Coverage 60.14% 60.14% -0.01% 
==========================================
Files 191 191 Lines 6808 6802 -6 ==========================================
- Hits 4095 4091 -4 + Misses 2099 2098 -1 + Partials 614 613 -1 

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[apricote]

This is a potentially breaking change. Even though this flag shows a warning since 2018, we should try to avoid making breaking changes on purpose.

I have created a v2 milestone and added this PR to it, so we have a list of things to tackle if we decide to work on it.

[github-actions]

This PR has been marked as stale because it has not had recent activity. The bot will close the PR if no further action occurs.

[github-actions]

This PR has been marked as stale because it has not had recent activity. The bot will close the PR if no further action occurs.