ci(github actions): add Docker build and test

.github/workflows/docker.yml

+name: Docker
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  build:
+    runs-on: ubuntu-20.04
+    timeout-minutes: 40
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build container image
+      run: docker build -t test-container-image .
+    - name: Launch container
+      run: docker run -dp 3000:3000 test-container-image
+      timeout-minutes: 5
+    - run: docker ps
+    - name: Wait for Service to start
+      run: while ! curl -s localhost:3000/health; do sleep 1; done
+      timeout-minutes: 1
+    - name: Check API health
+      run: curl -s localhost:3000/health
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