ci: use patched version of cargo-check-external-types to fix CI failure (#6937)

Author: taiki-e

.github/workflows/ci.yml

@@ -1035,7 +1035,7 @@ jobs:
  rust:
  # `check-external-types` requires a specific Rust nightly version. See
  # the README for details: https://github.com/awslabs/cargo-check-external-types
- - nightly-2023-10-21
+ - nightly-2024-06-30
  steps:
  - uses: actions/checkout@v4
  - name: Install Rust ${{ matrix.rust }}
@@ -1046,7 +1046,10 @@ jobs:
  - name: Install cargo-check-external-types
  uses: taiki-e/cache-cargo-install-action@v1
  with:
- tool: cargo-check-external-types@0.1.10
+ tool: cargo-check-external-types
+ # TODO: install from crates.io once https://github.com/awslabs/cargo-check-external-types/pull/183 merged and released.
+ git: https://github.com/taiki-e/cargo-check-external-types.git
+ rev: 83a8d29
  - name: check-external-types
  run: cargo check-external-types --all-features
  working-directory: tokio