first stab at using github actions

.github/workflows/build-and-push-images.yml

+name: Build and push images
+on:
+  push:
+    branches: ['master']
+
+jobs:
+  build-and-push-image:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Log in to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: true
+          tags: ${{ github.repository }}/9
+          build-args: |
+            ALPINE_VERSION=3.6