chore(ci): improve error handling and push only ref

.gitea/workflows/sync.yaml

@@ -17,7 +17,7 @@ jobs:
     - uses: actions/checkout@v4.2.2
     - name: Configure SSH client
       run: |
-        mkdir ~/.ssh
+        mkdir ~/.ssh || true
         chmod 0700 ~/.ssh
 
         echo "${AUR_SSH_KEY}" | base64 --decode > ~/.ssh/id
@@ -30,7 +30,7 @@ jobs:
         EOF
     - name: Push
       run: |
-        git push ssh://aur@aur.archlinux.org/mint-backgrounds.git
+        git push ssh://aur@aur.archlinux.org/mint-backgrounds.git ${{ github.ref }}
     - name: Remove SSH client configuration
       run: |
         rm -rf ~/.ssh