CI: cargo fmt and cargo clippy

.github/workflows/check.yaml

@@ -0,0 +1,44 @@
+name: check
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+  schedule:
+    - cron: '48 20 * * 4'
+
+env:
+  # Make sure cargo commands not only fail on hard errors but also on warnings
+  # so we do not accidentally miss newly introduced warnings.
+  RUSTFLAGS: -D warnings
+
+jobs:
+  fmt:
+    name: cargo fmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          components: rustfmt
+          override: true
+      - uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
+  clippy:
+    name: cargo clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          components: clippy
+          override: true
+      - uses: Swatinem/rust-cache@v2
+      - uses: actions-rs/clippy-check@v1