build: add GitHub action for testing

.github/workflows/test.yml

@@ -0,0 +1,37 @@
+name: test
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out
+        uses: actions/checkout@v3
+      - name: Update Rust
+        run: |
+          rustup update
+          rustup toolchain install nightly
+          rustup component add rustfmt --toolchain nightly
+      - name: Set up cargo cache
+        uses: actions/cache@v3
+        continue-on-error: false
+        with:
+          path: |
+            ~/.cargo/bin/
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+            target/
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: ${{ runner.os }}-cargo-
+      - name: Check code formatting
+        run: cargo +nightly fmt --all --check
+      - name: Lint
+        run: cargo clippy -- -D warnings
+      - name: Test
+        run: cargo test