chore(ci): check unused dependencies (#3334)

And move itoa to http1 feature

.github/workflows/CI.yml

@@ -25,6 +25,7 @@ jobs:
       - ffi-header
       - doc
       - check-external-types
+      - udeps
     steps:
       - run: exit 0
 
@@ -232,3 +233,22 @@ jobs:
 
       - name: check-external-types
         run: cargo check-external-types --config .github/workflows/external-types.toml
+
+  udeps:
+    needs: [style]
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@nightly
+
+      - name: Install cargo-udeps
+        uses: taiki-e/install-action@cargo-udeps
+
+      - name: Check unused dependencies on default features
+        run: cargo udeps
+
+      - name: Check unused dependencies on full features
+        run: cargo udeps --features full

Cargo.toml

@@ -28,13 +28,13 @@ http-body = "=1.0.0-rc.2"
 http-body-util = { version = "=0.1.0-rc.3", optional = true }
 httparse = "1.8"
 h2 = { version = "0.3.9", optional = true }
-itoa = "1"
 pin-project-lite = "0.2.4"
 tokio = { version = "1", features = ["sync"] }
 
 # Optional
 
 httpdate = { version = "1.0", optional = true }
+itoa = { version = "1", optional = true }
 libc = { version = "0.2", optional = true }
 tracing = { version = "0.1", default-features = false, features = ["std"], optional = true }
 want = { version = "0.3", optional = true }
@@ -74,7 +74,7 @@ full = [
 ]
 
 # HTTP versions
-http1 = []
+http1 = ["dep:itoa"]
 http2 = ["dep:h2"]
 
 # Client/Server