Add a multi-architecture docker build. (#98)

* Add a multi-arch docker build.

* Remove caching

.github/workflows/docker-build.yml

@@ -0,0 +1,36 @@
+name: Docker Multi-Architecture Build
+
+on:
+  push:
+    paths-ignore:
+      - "**.md"
+    branches:
+      - master
+
+jobs:
+  build-docker:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+        with:
+          platforms: all
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v1
+        with:
+          version: latest
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+      - name: Build and push
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          file: ./Dockerfile
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: spikecodes/libreddit:latest