Added github actions to test PR with a docker build

.github/workflows/docker-pr.yml

@@ -0,0 +1,42 @@
+name: docker-pr
+
+on:
+  pull_request:
+    branches: [master]
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    steps:
+      - name: checkout code
+        uses: actions/checkout@v2
+      - name: Set hash
+        id: vars
+        run: echo "::set-output name=sha_short::$(git rev-parse --short HEAD)"
+      - name: Get current date
+        id: date
+        run: echo "::set-output name=date::$(date +'%Y-%m-%d')"
+      - name: create-json
+        id: create-json
+        uses: jsdaniell/create-json@1.1.2
+        with:
+          name: "version.json"
+          json: '{"type": "docker", "tag": "nightly", "commit": "${{ steps.vars.outputs.sha_short }}", "date": "${{ steps.date.outputs.date }}"}'
+          dir: 'backend/'
+      - name: setup platform emulator
+        uses: docker/setup-qemu-action@v1
+      - name: setup multi-arch docker build
+        uses: docker/setup-buildx-action@v1
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: build & push images
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          file: ./Dockerfile
+          platforms: linux/amd64,linux/arm,linux/arm64/v8
+          push: false
+          tags: tzahi12345/youtubedl-material:nightly-pr