Add a GitHub action CI

.github/workflows/ci.yml

@@ -0,0 +1,34 @@
+name: ci
+on: [push, pull_request]
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        rust:
+          - 1.46.0
+          - 1.51.0
+          - 1.56.0
+          - stable
+          - beta
+          - nightly
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install Rust ${{ matrix.rust }}
+        uses: actions-rs/toolchain@v1
+        with:
+            toolchain: ${{ matrix.rust }}
+            override: true
+            profile: minimal
+      - name: Run cargo build
+        uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: --verbose
+      - name: Run cargo test
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --verbose