Improve GitHub actions

Add tags and labels when new Docker images are published
Test build Docker image on push and pull request
Release image on GitHub Docker registry

.github/dependabot.yml

@@ -0,0 +1,8 @@
+version: 2
+updates:
+
+  # Maintain dependencies for GitHub Actions
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"

.github/workflows/publish-docker-image.yml

@@ -3,26 +3,48 @@ name: Publish Docker Image
 on:
   push:
     branches:
-      - 'master'
-  pull_request:
-    branches:
-      - 'master'
+      - 'latest'
+      - 'develop'
+    tags:
+      - 'v*'
 
 jobs:
-  docker:
+  publish-image:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
         uses: actions/checkout@v2
+
       - name: Login to DockerHub
-        if: github.event_name != 'pull_request'
         uses: docker/#-action@v1
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
-      - name: Build and push
+
+      - name: Log in GitHub Docker registry
+        uses: docker/#-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@v3
+        with:
+          images: |
+            nevermendel/docker-xelatex-awesome-cv
+            ghcr.io/${{ github.repository }}
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+      
+      - name: Build and push Docker images
         uses: docker/build-push-action@v2
         with:
           context: .
-          push: ${{ github.event_name != 'pull_request' }}
-          tags: nevermendel/docker-xelatex-awesome-cv:latest
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

.github/workflows/test-docker-image.yml

@@ -0,0 +1,22 @@
+name: Test Build Docker Image
+
+on:
+  push:
+    branches:
+      - '*'
+  pull_request:
+    branches:
+      - '*'
+
+jobs:
+  test-image:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Build Docker image
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: false