Bump actions/checkout from 4 to 6 (#433)

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

Author: dependabot[bot]

.github/workflows/create_release.yml

@@ -7,7 +7,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Create a Release
       uses: elgohr/Github-Release-Action@v5
       env:

.github/workflows/create_tag.yml

@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           ref: master
       - uses: jacopocarlini/action-autotag@3.0.0

.github/workflows/dart.yml

@@ -15,7 +15,7 @@ jobs:
         # Test with at least the declared minimum Dart version
         sdk: ['3.5', stable]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: dart-lang/setup-dart@v1
         with:
           sdk: ${{ matrix.sdk }}

.github/workflows/publish_demos.yml

@@ -10,7 +10,7 @@ jobs:
       image: dart
     steps:
       - name: Checkout 🛎️
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Install rsync 📚
         run: |

.github/workflows/triage.yml

@@ -8,7 +8,7 @@ jobs:
     name: Assign Rob
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Apply untriaged label
         uses: actions/github-script@v8
         with: