Lowercase env.IMAGE_REGISTRY

Workaround for a bug in push-to-ghcr that makes it impossible to push your image if your GitHub username contains capital letters.

.github/workflows/build.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
-    steps:
+    steps: 
       # Checkout push-to-registry action github repository
       - name: Checkout Push to Registry action
         uses: actions/checkout@v2
@@ -32,6 +32,14 @@ jobs:
           tags: ${{ env.IMAGE_TAGS }}
           oci: true
 
+      # Workaround bug where capital letters in your GitHub user name make it impossible to push to GHCR.
+      # https://github.com/macbre/push-to-ghcr/issues/12
+      - name: Lowercase Registry
+        id: registry_case
+        uses: ASzc/change-string-case-action@v5
+        with:
+          string: ${{ env.IMAGE_REGISTRY }}
+
       # Push the image to GHCR (Image Registry)
       - name: Push To GHCR
         uses: redhat-actions/push-to-registry@v2
@@ -39,7 +47,7 @@ jobs:
         with:
           image: ${{ steps.build_image.outputs.image }}
           tags: ${{ steps.build_image.outputs.tags }}
-          registry: ${{ env.IMAGE_REGISTRY }}
+          registry: ${{ steps.registry_case.outputs.lowercase }}
           username: ${{ env.REGISTRY_USER }}
           password: ${{ env.REGISTRY_PASSWORD }}
           extra-args: |