Add ghcr.io prefix to metadata

Author: ccremer

.github/workflows/build.yml

@@ -16,7 +16,7 @@ jobs:
         id: meta
         uses: docker/metadata-action@v3
         with:
-          images: ${{ github.repository }}
+          images: ghcr.io/${{ github.repository }}
 
       - name: Build
         uses: docker/build-push-action@v2

.github/workflows/release.yml

@@ -17,7 +17,7 @@ jobs:
         id: meta
         uses: docker/metadata-action@v3
         with:
-          images: ${{ github.repository }}
+          images: ghcr.io/${{ github.repository }}
 
       - name: Login to GHCR
         uses: docker/login-action@v1