fix: reset author and sign during backport

.backportrc.json

@@ -1,6 +1,7 @@
 {
   "repoOwner": "terrapkg",
   "repoName": "packages",
+  "resetAuthor": true,
   "targetBranchChoices": ["f38", "f39", "f40", "frawhide"],
   "branchLabelMapping": {
     "^sync-(.+)$": "$1"

.github/workflows/sync.yml

@@ -10,6 +10,18 @@ jobs:
     runs-on: ubuntu-latest
     if: github.event.pull_request.merged
     steps:
+      - name: Install SSH signing key
+        run: |
+          mkdir -p ${{ runner.temp }}
+          echo "${{ secrets.SSH_SIGNING_KEY }}" > ${{ runner.temp }}/signing_key
+          chmod 0700 ${{ runner.temp }}/signing_key
+
+      - name: Setup Raboneko Signing
+        run: |
+          git config --global gpg.format "ssh"
+          git config --global user.signingkey "${{ runner.temp }}/signing_key"
+          git config --global commit.gpgsign true
+
       - name: Backport Action
         uses: sorenlouv/[email protected]
         with: