Bump actions/checkout from 5 to 6 in the all-github-actions group

Bumps the all-github-actions group with 1 update: [actions/checkout](https://github.com/actions/checkout).


Updates `actions/checkout` from 5 to 6
- [Release notes](https://github.com/actions/checkout/releases)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: all-github-actions
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/coverage.yml

@@ -19,7 +19,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository == 'flutter/flutter' }}
     steps:
-      - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd
+      - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
       - name: ./bin/flutter test --coverage
         run: pushd packages/flutter;../../bin/flutter test --coverage -j 1;popd
       - name: upload coverage

.github/workflows/easy-cp.yml

@@ -46,7 +46,7 @@ jobs:
         run: |
           echo "COMMIT_SHA=$(echo ${{ github.event.pull_request.merge_commit_sha }})" >> $GITHUB_ENV
       - name: Checkout Flutter Repo
-        uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd
+        uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
         with:
           repository: flutteractionsbot/flutter
           path: flutter