ci: Update GitHub workflow to build and push on PR merge

- Add trigger for PR merge to master branch
- Update Docker action versions
- Add more comprehensive tag strategy

Author: Luis Rodríguez

.github/workflows/release.yml

@@ -3,9 +3,13 @@ name: Publish Docker image
 on:
   release:
     types: [published]
+  pull_request:
+    types: [closed]
+    branches: [master]
 
 jobs:
   push_to_registries:
+    if: github.event_name == 'release' || (github.event_name == 'pull_request' && github.event.pull_request.merged == true)
     name: Push Docker image to multiple registries
     runs-on: ubuntu-latest
     permissions:
@@ -22,21 +26,26 @@ jobs:
         uses: docker/setup-buildx-action@v2
 
       - name: Log in to the Container registry
-        uses: docker/login-action@f054a8b539a109f9f41c372932f1ae047eff08c9
+        uses: docker/login-action@v2
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Extract metadata (tags, labels) for Docker
         id: meta
-        uses: docker/metadata-action@98669ae865ea3cffbcbaa878cf57c20bbf1c6c38
+        uses: docker/metadata-action@v4
         with:
           images: |
             ghcr.io/${{ github.repository }}
+          tags: |
+            type=semver,pattern={{version}}
+            type=ref,event=branch
+            type=sha,format=short
+            latest
 
       - name: Build and push Docker images
-        uses: docker/build-push-action@v3
+        uses: docker/build-push-action@v4
         with:
           context: .
           push: true