Add github actions workflow file

.github/workflows/ci.yml

@@ -0,0 +1,40 @@
+on: [push, pull_request]
+
+name: Continuous integration
+
+jobs:
+  check:
+    name: Check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: Swatinem/rust-cache@v2
+      - uses: dsherret/rust-toolchain-file@v1
+      - run: cargo check
+
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: Swatinem/rust-cache@v2
+      - uses: dsherret/rust-toolchain-file@v1
+      - run: cargo test
+
+  fmt:
+    name: Rustfmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: Swatinem/rust-cache@v2
+      - uses: dsherret/rust-toolchain-file@v1
+      - run: cargo fmt --all -- --check
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: Swatinem/rust-cache@v2
+      - uses: dsherret/rust-toolchain-file@v1
+      - run: cargo clippy -- -D warnings