ci(deps): bump actions/checkout from 4 to 6 (#1)

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] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Anantha Krishnan <ananthakrrishnan7@gmail.com>

Author: dependabot[bot]

.github/workflows/docs.yml

@@ -31,7 +31,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
 

.github/workflows/release.yml

@@ -33,7 +33,7 @@ jobs:
     outputs:
       version: ${{ steps.parse.outputs.version }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - id: parse
         name: Extract version from tag
@@ -62,7 +62,7 @@ jobs:
     runs-on: ubuntu-latest
     environment: pypi    # Required by the PyPI Trusted Publisher rule.
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - uses: astral-sh/setup-uv@v4
         with:
@@ -79,7 +79,7 @@ jobs:
     needs: pypi
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0    # Need full history for ``--generate-notes``.