ci: bump korthout/backport-action from 4.5.0 to 4.5.1 (#2305)

Link: https://github.com/nix-community/stylix/pull/2305

Reviewed-by: NAHO <trueNAHO@users.noreply.github.com>
(cherry picked from commit 18ed8d2702)

.github/workflows/backport.yml

@@ -45,7 +45,7 @@ jobs:
           ref: ${{ github.event.pull_request.head.sha }}
           token: ${{ steps.app-token.outputs.token }}
 
-      - uses: korthout/backport-action@v4.5.0
+      - uses: korthout/backport-action@v4.5.1
         id: backport
         with:
           github_token: ${{ steps.app-token.outputs.token }}