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/maven.yml

@@ -38,7 +38,7 @@ jobs:
     steps:
 
       - name: Checkout Arquillian
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: 'arquillian/arquillian-container-jetty'
           ref: 'master'
@@ -54,7 +54,7 @@ jobs:
         run: mvn install -B -U
 
       - name: Checkout Websocket TCK
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: 'jakartaee/websocket'
           ref: 'main'
@@ -73,7 +73,7 @@ jobs:
         run: ./mvnw -V -B -U clean install -DskipTests -e
 
       - name: Checkout TCK Run
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set up Maven
         run: mvn --errors --batch-mode --show-version wrapper:wrapper "-Dmaven=3.9.11"