Add docker publish action

.github/workflows/publish-docker.yml

@@ -0,0 +1,45 @@
+name: Build and Publish Docker Image
+
+on:
+  push:
+    branches:
+    - master
+    tags:
+    - v*
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+      with:
+        submodules: 'recursive'
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v1
+    - name: Set up Docker Buildx
+      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: Docker meta
+      id: docker_meta
+      uses: crazy-max/ghaction-docker-meta@v1
+      with:
+        images: opendronemap/clusterodm
+        tag-semver: |
+          {{version}}
+    - name: Build and push Docker image
+      id: docker_build
+      uses: docker/build-push-action@v2
+      with:
+        file: ./Dockerfile
+        platforms: linux/amd64,linux/arm64
+        push: true
+        tags: |
+          ${{ steps.docker_meta.outputs.tags }}
+          opendronemap/clusterodm:latest
+    - name: Image digest
+      run: echo ${{ steps.docker_build.outputs.digest }}