chore(deps): bump actions/checkout from 5 to 6 (#544)

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

Author: dependabot[bot]

.github/workflows/build-docs.yml

@@ -14,7 +14,7 @@ jobs:
   build_doc:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Derive nightly version
         run: |

.github/workflows/build-gems.yml

@@ -38,7 +38,7 @@ jobs:
       matrix:
         ruby-platform: ${{ fromJSON(needs.ci-data.outputs.result).supported-ruby-platforms }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: ruby/setup-ruby@v1
         with:
@@ -68,7 +68,7 @@ jobs:
         os: ["ubuntu-latest"]
         ruby: ["3.4"]
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: oxidize-rb/actions/setup-ruby-and-rust@v1
         with:

.github/workflows/ci.yml

@@ -40,7 +40,7 @@ jobs:
           # - os: windows-latest
           #   ruby: mswin
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Remove Gemfile.lock
         run: rm Gemfile.lock

.github/workflows/memcheck.yml

@@ -34,7 +34,7 @@ jobs:
     name: Memcheck
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: oxidize-rb/actions/setup-ruby-and-rust@v1
         with:

.github/workflows/release.yml

@@ -38,7 +38,7 @@ jobs:
       matrix:
         ruby-platform: ${{ fromJSON(needs.ci-data.outputs.result).supported-ruby-platforms }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: ruby/setup-ruby@v1
         with:
@@ -69,7 +69,7 @@ jobs:
     needs: build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: oxidize-rb/actions/setup-ruby-and-rust@v1
         with: