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/chipyard-chisel7.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Install DTC (device-tree-compiler)
         run: |

.github/workflows/chipyard-full-flow.yml

@@ -50,7 +50,7 @@ jobs:
     outputs:
       needs-rtl: ${{ steps.filter.outputs.all_count != steps.filter.outputs.skip-rtl_count }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Git workaround
         uses: ./.github/actions/git-workaround
       - uses: dorny/paths-filter@v3
@@ -87,7 +87,7 @@ jobs:
             rm -rf ${{ github.workspace }}/* || true
             rm -rf ${{ github.workspace }}/.* || true
             ls -alh .
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Setup repo copy
         run: |
           git clone $GITHUB_WORKSPACE ${{ env.REMOTE_WORK_DIR }}