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/alpine.yml

@@ -12,14 +12,14 @@ jobs:
     container: alpine
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install dependencies
         run: |
           apk add build-base openssl-dev zlib-dev pcre2-dev \
                   cmake git grpc-dev protobuf-dev \
                   python3
       - name: Checkout nginx
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: nginx/nginx
           path: nginx

.github/workflows/ubuntu.yml

@@ -11,13 +11,13 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install dependencies
         run: |
           sudo apt-get update
           sudo apt-get install -y cmake libc-ares-dev
       - name: Checkout nginx
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: nginx/nginx
           path: nginx