Add docker GPU build action

.github/workflows/publish-docker-gpu.yaml

@@ -0,0 +1,38 @@
+name: Publish Docker
+
+# Triggered by ODM build (after docker push)
+on:
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+    - 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 }}
+    # Use the repository information of the checked-out code to format docker tags
+    - name: Docker meta
+      id: docker_meta
+      uses: crazy-max/ghaction-docker-meta@v1
+      with:
+        images: opendronemap/nodeodm
+        tag-semver: |
+          {{version}}
+    - name: Build and push Docker image
+      id: docker_build
+      uses: docker/build-push-action@v2
+      with:
+        file: ./Dockerfile.gpu
+        platforms: linux/amd64
+        push: true
+        tags: |
+          opendronemap/nodeodm:gpu