Add missing merge arg

Author: pawelirh

.github/workflows/release-repository.yaml

@@ -56,7 +56,7 @@ jobs:
               if: ${{ fromJSON(github.event.inputs.automatic_mode) == true }}
               run: |
                   gh pr merge ${{ steps.create_release_candidate.outputs.created_branch }} \
-                  --delete-branch
+                  --merge --delete-branch
 
             - name: Create tag
               if: ${{ fromJSON(github.event.inputs.automatic_mode) == true }}
@@ -99,4 +99,4 @@ jobs:
               if: ${{ github.event.inputs.target_branch != env.MAIN_BRANCH && fromJSON(github.event.inputs.automatic_mode) == true }}
               run: |
                   gh pr merge ${{ github.event.inputs.target_branch }} \
-                  --delete-branch
+                  --merge --delete-branch