.github/workflows/docker-image.yml: add docker builds on push/pr/daily

.github/workflows/docker-image.yml

@@ -0,0 +1,29 @@
+name: Docker Image CI
+
+on:
+  push:
+    branches:
+    - master
+    - dev
+  pull_request:
+    branches:
+    - master
+    - dev
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+  schedule:
+  - cron: "0 4 * * 0-6"
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        submodules: 'recursive'
+    - name: Build the Docker image
+      run: docker build . --file Dockerfile --tag goryn-pathfinder-containers:$(date +%s)
+