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] <support@github.com>

Author: dependabot[bot]

.github/workflows/Docs.yml

@@ -10,7 +10,7 @@ jobs:
   docs:
       runs-on: ubuntu-latest
       steps:
-        - uses: actions/checkout@v4
+        - uses: actions/checkout@v6
         - uses: julia-actions/cache@v2
         - uses: julia-actions/julia-buildpkg@latest
         - uses: julia-actions/julia-docdeploy@latest

.github/workflows/Invalidations.yml

@@ -19,13 +19,13 @@ jobs:
     - uses: julia-actions/setup-julia@v1
       with:
         version: '1.10'
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - uses: julia-actions/cache@v2
     - uses: julia-actions/julia-buildpkg@v1
     - uses: julia-actions/julia-invalidations@v1
       id: invs_pr
 
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
       with:
         ref: ${{ github.event.repository.default_branch }}
     - uses: julia-actions/julia-buildpkg@v1