chore(actions): include CI action for checks

I just yanked this from df8570b16e/.github/workflows/ci.yaml.

.github/ci.yaml

@@ -0,0 +1,34 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  ci:
+    name: CI
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+        with:
+          submodules: true
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt, clippy
+
+      - name: Rustfmt
+        run: cargo fmt -- --check
+
+      - name: Build
+        run: cargo build --locked
+
+      - name: Clippy
+        run: cargo clippy
+
+      - name: Test
+        run: cargo test --lib