build(deps): bump actions/checkout from 5 to 6

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] <[email protected]>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -23,7 +23,7 @@ jobs:
       # Checkout repos
       #
       - name: Checkout cgroups
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           path: src/github.com/containerd/cgroups
           fetch-depth: 25
@@ -54,7 +54,7 @@ jobs:
 
     steps:
       - name: Checkout cgroups
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           path: src/github.com/containerd/cgroups
 
@@ -96,7 +96,7 @@ jobs:
           free -mt
 
       - name: Checkout cgroups
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           path: src/github.com/containerd/cgroups
 
@@ -158,7 +158,7 @@ jobs:
 
     steps:
       - name: Checkout cgroups
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           path: src/github.com/containerd/cgroups
 
@@ -182,7 +182,7 @@ jobs:
 
     steps:
       - name: Checkout cgroups
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           path: src/github.com/containerd/cgroups