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/check-formatting.yml

@@ -10,7 +10,7 @@ jobs:
   format:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup Node.js
         uses: actions/setup-node@v4

.github/workflows/check-links.yml

@@ -12,7 +12,7 @@ jobs:
     if: github.event_name != 'pull_request' || github.actor != 'codatbot' 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Set up Node.js
         uses: actions/setup-node@v4

.github/workflows/check-markdown-lint.yml

@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Set up Node.js
         uses: actions/setup-node@v4

.github/workflows/check-readability.yml

@@ -9,7 +9,7 @@ jobs:
         runs-on: ubuntu-latest
         steps:
             - name: Checkout repo with history
-              uses: actions/checkout@v4
+              uses: actions/checkout@v6
               with:
                   fetch-depth: 0
             - uses: Rebilly/lexi@v2

.github/workflows/check-spelling.yml

@@ -10,7 +10,7 @@ jobs:
   spell-check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup Node.js
         uses: actions/setup-node@v4

.github/workflows/check-vale.yml

@@ -22,7 +22,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Vale Linter
         uses: errata-ai/vale-action@reviewdog