CI: revert to a simpler version with hardcoded values.

Somehow if env vars weren't set, we'd still use dockerhub

.github/workflows/docker-image.yml

@@ -19,21 +19,16 @@ jobs:
     - name: Log in to the Container registry
       uses: docker/login-action@65b78e6e13532edd9afa3aa52ac7964289d1a9c1
       with:
-        registry: ${{ env.REGISTRY }}
+        registry: ghcr.io
         username: ${{ github.actor }}
         password: ${{ secrets.GITHUB_TOKEN }}
 
-    - name: Extract metadata (tags, labels) for Docker
-      id: meta
-      uses: docker/metadata-action@9ec57ed1fcdbf14dcef7dfbe97b2010124a938b7
-      with:
-        images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
-
     - name: Build and push Docker image
       id: push
       uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
       with:
         context: .
         push: true
-        tags: ${{ steps.meta.outputs.tags }}
-        labels: ${{ steps.meta.outputs.labels }}
+        tags: |
+           ghcr.io/educredentials/admin-dashboard-claim-page:latest
+           ghcr.io/educredentials/admin-dashboard-claim-page:${{ github.sha }}