add a continuous integration workflow

.github/workflow/ci.yml

@@ -0,0 +1,37 @@
+name: Continuous Integration
+
+on:
+  pull_request:
+    branches:
+      - master
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    name: Build Docker image and run end-to-end tests
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code from Github
+        uses: actions/checkout@v3
+      - name: Run end-to-end tests
+        run: >
+          docker-compose --profile testing up
+          --build
+          --exit-code-from test
+      - name: Login to Docker Hub
+        uses: docker/login-action@v2
+        if: ${{ github.event_name == 'push' }}
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Push image to Docker Hub
+        uses: docker/[email protected]
+        if: ${{ github.event_name == 'push' }}
+        with:
+          context: ./web
+          push: true
+          tags: |
+            ${{ secrets.DOCKERHUB_USERNAME }}/page-tracker:${{ github.sha }}
+            ${{ secrets.DOCKERHUB_USERNAME }}/page-tracker:latest