actions: use login action, bump checkout

.github/workflows/docker.yml

@@ -14,14 +14,14 @@ jobs:
 
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Log in to Gitea Package Registry
-        run: echo "${{ secrets.PACKAGE_TOKEN }}" | docker login "$SERVER_URL" -u "$USERNAME" --password-stdin
-        env:
-          SERVER_URL: ${{ secrets.SERVER_URL }}
-          USERNAME: ${{ secrets.USERNAME }}
-          PACKAGE_TOKEN: ${{ secrets.PACKAGE_TOKEN }}
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ secrets.SERVER_URL }}
+          username: ${{ secrets.USERNAME }}
+          password: ${{ secrets.PACKAGE_TOKEN }}
 
       - name: Build Docker Image
         run: docker build -t git.pontusmail.org/librecloud/mail-connect:latest .