Add CI formatting and doctest checks

.github/workflows/ci.yml

@@ -7,6 +7,16 @@ on:
   pull_request:
 
 jobs:
+  format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt
+      - name: Check Rust formatting
+        run: cargo fmt --all -- --check
+
   test-linux:
     runs-on: ubuntu-latest
     steps:
@@ -22,21 +32,33 @@ jobs:
             libpango1.0-dev \
             libatk1.0-dev \
             libcairo2-dev
+      - name: Cargo check
+        run: cargo check --all-targets
       - name: Cargo test
         run: xvfb-run -a cargo test --all-targets
+      - name: Cargo test doctests
+        run: cargo test --doc
 
   test-macos:
     runs-on: macos-latest
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
+      - name: Cargo check
+        run: cargo check --all-targets
       - name: Cargo test
         run: cargo test --all-targets
+      - name: Cargo test doctests
+        run: cargo test --doc
 
   test-windows:
     runs-on: windows-latest
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
+      - name: Cargo check
+        run: cargo check --all-targets
       - name: Cargo test
         run: cargo test --all-targets
+      - name: Cargo test doctests
+        run: cargo test --doc