test docker build in CI

.github/workflows/build.yml

@@ -65,3 +65,15 @@ jobs:
         override: true
     - name: Run tests
       run: cargo test --features simd
+
+  docker_build:
+    name: Docker Image Build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Build Docker image
+        uses: docker/build-push-action@ad44023a93711e3deb337508980b4b5e9bcdc5dc
+        with:
+          context: .
+          push: false
+          tags: latest

Dockerfile

@@ -1,4 +1,4 @@
-FROM rust:1.53 as builder
+FROM rust:1.55 as builder
 WORKDIR /roapi_src
 COPY ./ /roapi_src
 RUN cargo install --locked --path ./roapi-http --bin roapi-http