Bump actions/checkout from 5.0.0 to 6.0.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@08c6903...1af3b93)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/sphinx-check.yml

@@ -9,7 +9,7 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps: 
-    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # version 5.0.0
+    - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # version 6.0.0
     - uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # version 6.0.0
       with:
         python-version: "3.12"

.github/workflows/sphinx.yml

@@ -18,7 +18,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps: 
-    - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # version 5.0.0
+    - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3 # version 6.0.0
     - uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # version 6.0.0
       with:
         python-version: "3.12"