chore(deps): bump actions/checkout from 5 to 6 (#955)

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/metadata-parser-validation.yml

@@ -12,7 +12,7 @@ jobs:
     outputs:
       matrix: ${{ steps.set-conversion-settings.outputs.matrix }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - id: set-conversion-settings
         run: echo "matrix=$(ls conversion-settings/*.json | sed 's/.*\///' | sed 's/\.[^.]*$//' | jq -R -s -c 'split("\n")[:-1]')" >> $GITHUB_OUTPUT
 
@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         submodules: recursive
 

.github/workflows/openapi-parser-validation.yml

@@ -13,7 +13,7 @@ jobs:
     outputs:
       matrix: ${{ steps.set-conversion-settings.outputs.matrix }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - id: set-conversion-settings
         run: echo "matrix=$(ls conversion-settings/*.json | sed 's/.*\///' | sed 's/\.[^.]*$//' | jq -R -s -c 'split("\n")[:-1]')" >> $GITHUB_OUTPUT
 
@@ -28,7 +28,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         submodules: recursive
     - name: Setup .NET

.github/workflows/validate-typespec-changes.yml

@@ -13,7 +13,7 @@ jobs:
       run:
         working-directory: additions
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Setup NodeJs
         uses: actions/setup-node@v6