Bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/auto-merge.yml

@@ -13,7 +13,7 @@ jobs:
     if: github.actor == 'dependabot[bot]'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
       - uses: dtolnay/rust-toolchain@stable

.github/workflows/release.yml

@@ -40,7 +40,7 @@ jobs:
 
     runs-on: ${{ matrix.host_os }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
 
       - name: Prepare

.github/workflows/rust.yml

@@ -23,7 +23,7 @@ jobs:
     runs-on: ${{ matrix.os }}
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: dtolnay/rust-toolchain@stable
     - name: rustfmt
       run: cargo fmt --all -- --check
@@ -51,7 +51,7 @@ jobs:
         os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - name: Check semver
         if: ${{ !cancelled() }}