fix case issue with path

Author: jaschadub

.github/workflows/docker.yml

@@ -12,7 +12,6 @@ on:
 
 env:
   REGISTRY: ghcr.io
-  IMAGE_NAME: ${{ github.repository }}
 
 jobs:
   build-and-push:
@@ -25,6 +24,9 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v4
 
+    - name: Set lowercase image name
+      run: echo "IMAGE_NAME=$(echo '${{ github.repository }}' | tr '[:upper:]' '[:lower:]')" >> $GITHUB_ENV
+
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v3