workflows: make homebrew lowercase again for Docker.

Otherwise this fails.

.github/workflows/docker.yml

@@ -36,10 +36,10 @@ jobs:
           brew_version=${GITHUB_REF:10}
           echo "::set-env name=brew_version::$brew_version"
           echo ${{secrets.HOMEBREW_GITHUB_PACKAGES_API_TOKEN}} | docker login ghcr.io -u BrewTestBot --password-stdin
-          docker tag brew "ghcr.io/Homebrew/ubuntu${{matrix.version}}:$brew_version"
-          docker push "ghcr.io/Homebrew/ubuntu${{matrix.version}}:$brew_version"
-          docker tag brew "ghcr.io/Homebrew/ubuntu${{matrix.version}}:latest"
-          docker push "ghcr.io/Homebrew/ubuntu${{matrix.version}}:latest"
+          docker tag brew "ghcr.io/homebrew/ubuntu${{matrix.version}}:$brew_version"
+          docker push "ghcr.io/homebrew/ubuntu${{matrix.version}}:$brew_version"
+          docker tag brew "ghcr.io/homebrew/ubuntu${{matrix.version}}:latest"
+          docker push "ghcr.io/homebrew/ubuntu${{matrix.version}}:latest"
 
       - name: Deploy the tagged Docker image to Docker Hub
         if: startsWith(github.ref, 'refs/tags/')
@@ -53,10 +53,10 @@ jobs:
       - name: Deploy the homebrew/brew Docker image to GitHub Packages and Docker Hub
         if: startsWith(github.ref, 'refs/tags/') && matrix.version == '20.04'
         run: |
-          docker tag brew "ghcr.io/Homebrew/brew:$brew_version"
-          docker push "ghcr.io/Homebrew/brew:$brew_version"
-          docker tag brew "ghcr.io/Homebrew/brew:latest"
-          docker push "ghcr.io/Homebrew/brew:latest"
+          docker tag brew "ghcr.io/homebrew/brew:$brew_version"
+          docker push "ghcr.io/homebrew/brew:$brew_version"
+          docker tag brew "ghcr.io/homebrew/brew:latest"
+          docker push "ghcr.io/homebrew/brew:latest"
           docker tag brew "homebrew/brew:$brew_version"
           docker push "homebrew/brew:$brew_version"
           docker tag brew "homebrew/brew:latest"

.github/workflows/tests.yml

@@ -143,8 +143,8 @@ jobs:
       if: matrix.os == 'ubuntu-latest' && github.ref == 'refs/heads/master'
       run: |
         echo ${{secrets.HOMEBREW_GITHUB_PACKAGES_API_TOKEN}} | docker login ghcr.io -u BrewTestBot --password-stdin
-        docker tag brew "ghcr.io/Homebrew/ubuntu16.04:master"
-        docker push "ghcr.io/Homebrew/ubuntu16.04:master"
+        docker tag brew "ghcr.io/homebrew/ubuntu16.04:master"
+        docker push "ghcr.io/homebrew/ubuntu16.04:master"
         echo ${{secrets.DOCKER_TOKEN}} | docker login -u brewtestbot --password-stdin
         docker tag brew "homebrew/ubuntu16.04:master"
         docker push "homebrew/ubuntu16.04:master"