Fixes #3871

Proposed changes

Use git branch -D instead of git branch -d when explicitly deleting unmerged branches.

Screenshots

Test methodology

• Manual test to check if deleting unmerged branches works instead of return an error message from git.

Test environment(s)

• GIT 2.46.0
• Windows 10 Enterprise 22H2

Merge strategy

I agree that the maintainer squash merge this PR (if the commit message is clear).

✒️ I contribute this code under The Developer Certificate of Origin.