Prevent merge of outdated PRs on protected branches (#11012)

* Block PR on Outdated Branch

* finalize

* cleanup

* fix typo and sentences

thanks @guillep2k

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>
Co-authored-by: Lauris BH <lauris@nix.lv>

routers/api/v1/repo/branch.go

@@ -340,6 +340,7 @@ func CreateBranchProtection(ctx *context.APIContext, form api.CreateBranchProtec
 		DismissStaleApprovals:    form.DismissStaleApprovals,
 		RequireSignedCommits:     form.RequireSignedCommits,
 		ProtectedFilePatterns:    form.ProtectedFilePatterns,
+		BlockOnOutdatedBranch:    form.BlockOnOutdatedBranch,
 	}
 
 	err = models.UpdateProtectBranch(ctx.Repo.Repository, protectBranch, models.WhitelistOptions{
@@ -475,6 +476,10 @@ func EditBranchProtection(ctx *context.APIContext, form api.EditBranchProtection
 		protectBranch.ProtectedFilePatterns = *form.ProtectedFilePatterns
 	}
 
+	if form.BlockOnOutdatedBranch != nil {
+		protectBranch.BlockOnOutdatedBranch = *form.BlockOnOutdatedBranch
+	}
+
 	var whitelistUsers []int64
 	if form.PushWhitelistUsernames != nil {
 		whitelistUsers, err = models.GetUserIDsByNames(form.PushWhitelistUsernames, false)