Add ci to check external types (#250)

Author: tottoto

.github/workflows/rust.yml

@@ -55,3 +55,17 @@ jobs:
         uses: obi1kenobi/cargo-semver-checks-action@v2
         with:
           uses: dtolnay/rust-toolchain@stable
+
+  external-types:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: nightly-2025-08-06
+      - name: Install cargo-check-external-types
+        uses: taiki-e/cache-cargo-install-action@v2
+        with:
+          tool: [email protected]
+      - uses: Swatinem/rust-cache@v2
+      - run: cargo check-external-types --all-features

Cargo.toml

@@ -41,3 +41,9 @@ regex = ["dep:regex"]
 
 [lints.rust]
 unexpected_cfgs = { level = "warn", check-cfg = ['cfg(tokio_unstable)'] }
+
+[package.metadata.cargo_check_external_types]
+allowed_external_types = [
+  "bytes::*",
+  "tokio::*",
+]