Update actions/checkout@v4 -> v5

Author: dtolnay

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
         rust: [nightly, beta, stable, 1.56.0]
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{matrix.rust}}
@@ -41,7 +41,7 @@ jobs:
     env:
       RUSTDOCFLAGS: -Dwarnings
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: dtolnay/rust-toolchain@nightly
       - uses: dtolnay/install@cargo-docs-rs
       - run: cargo docs-rs
@@ -51,7 +51,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: dtolnay/rust-toolchain@clippy
       - run: cargo clippy -- -Dclippy::all
 
@@ -61,7 +61,7 @@ jobs:
     if: github.event_name != 'pull_request'
     timeout-minutes: 45
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: dtolnay/rust-toolchain@stable
       - uses: dtolnay/install@cargo-outdated
       - run: cargo outdated --workspace --exit-code 1