Move the GHCR authentication to the first set up step

.github/workflows/docker.yml

@@ -28,6 +28,7 @@ jobs:
         run: |
           sudo apt update
           curl -sSL https://install.python-poetry.org | python3 -
+          echo "${{ secrets.GITHUB_TOKEN }}" | docker login ghcr.io -u $ --password-stdin
 
       - name: Free up some disk space.
         uses: jlumbroso/free-disk-space@f68fdb76e2ea636224182cfb7377ff9a1708f9b8
@@ -40,6 +41,4 @@ jobs:
 
       - name: Push the Docker image.
         if: ${{ github.ref_name == github.event.repository.default_branch }}
-        run: |
-          echo "${{ secrets.GITHUB_TOKEN }}" | docker login ghcr.io -u $ --password-stdin
-          docker push $IMAGE_TAG
+        run: docker push $IMAGE_TAG