[c] fix docker login, again

.forgejo/workflows/build.yml

@@ -26,9 +26,11 @@ jobs:
           token: ${{ secrets.FORGEJO_TOKEN }}
 
       - name: 👤 Log in to the Container registry
-        id: login
-        run: |
-          echo "${{ secrets.FORGEJO_TOKEN }}" | docker login gitpot.org -u ${{ gitea.actor }} --password-stdin
+        uses: https://github.com/docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ gitea.actor }}
+          password: ${{ secrets.FORGEJO_TOKEN }}
 
       - name: ✏️ Extract metadata (tags, labels) for Docker
         id: meta