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/main.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     name: Run msync --noop against all modules
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Setup ruby
         uses: ruby/setup-ruby@v1
         with:
@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
     name: Run metadata_json_deps on all modules
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Setup ruby
         uses: ruby/setup-ruby@v1
         with:
@@ -40,7 +40,7 @@ jobs:
     runs-on: ubuntu-latest
     name: Prints a list of all modules with outdated modulesync_config version
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Setup ruby
         uses: ruby/setup-ruby@v1
         with:

.github/workflows/update.yml

@@ -32,7 +32,7 @@ jobs:
         #
         # the "ref: github.ref" is required for the tag to be properly checked out, as a workaround
         # for https://github.com/actions/checkout/issues/1638
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
           fetch-tags: true