build(deps): bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...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/check.yml

@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
     name: stable / fmt
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: true
       - name: Install stable
@@ -48,7 +48,7 @@ jobs:
         # Get early warning of new lints which are regularly introduced in beta channels.
         toolchain: [stable, beta]
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: true
       - name: Install ${{ matrix.toolchain }}
@@ -68,7 +68,7 @@ jobs:
   #   runs-on: ubuntu-latest
   #   name: semver
   #   steps:
-  #     - uses: actions/checkout@v5
+  #     - uses: actions/checkout@v6
   #       with:
   #         submodules: true
   #     - name: Install stable
@@ -83,7 +83,7 @@ jobs:
     runs-on: ubuntu-latest
     name: ubuntu / stable / features
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: true
       - name: Install stable
@@ -105,7 +105,7 @@ jobs:
   #       msrv: ["1.85.0"]
   #   name: ubuntu / ${{ matrix.msrv }}
   #   steps:
-  #     - uses: actions/checkout@v5
+  #     - uses: actions/checkout@v6
   #       with:
   #         submodules: true
   #     - name: Install ${{ matrix.msrv }}

.github/workflows/test.yml

@@ -28,7 +28,7 @@ jobs:
         # toolchain
         toolchain: [stable, beta]
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: true
       - name: Install ${{ matrix.toolchain }}
@@ -54,7 +54,7 @@ jobs:
   #   runs-on: ubuntu-latest
   #   name: ubuntu / stable / minimal-versions
   #   steps:
-  #     - uses: actions/checkout@v5
+  #     - uses: actions/checkout@v6
   #       with:
   #         submodules: true
   #     - name: Install stable
@@ -82,7 +82,7 @@ jobs:
       #   if: runner.os == Windows
       # - run: vcpkg install openssl:x64-windows-static-md
       #   if: runner.os == Windows
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: true
       - name: Install stable
@@ -117,7 +117,7 @@ jobs:
   #   runs-on: ubuntu-latest
   #   name: ubuntu / stable / coverage
   #   steps:
-  #     - uses: actions/checkout@v5
+  #     - uses: actions/checkout@v6
   #       with:
   #         submodules: true
   #     - name: Install stable