Bump actions/checkout from 5 to 6 (backport #1581) (#1583)

Author: mergify[bot]

.github/workflows/check_links.yml

@@ -10,7 +10,7 @@ jobs:
   check_links:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Restore lychee cache
         id: restore-cache
         uses: actions/cache/restore@v4

.github/workflows/ci-format.yml

@@ -15,7 +15,7 @@ jobs:
     name: Format
     runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-python@v6
         with:
           python-version: 3.10.4

.github/workflows/coverage-build.yml

@@ -20,7 +20,7 @@ jobs:
         with:
           required-ros-distributions: ${{ env.ROS_DISTRO }}
           use-ros2-testing: true
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: ros-tooling/[email protected]
         with:
           target-ros2-distro: ${{ env.ROS_DISTRO }}