Bump actions/checkout from 5 to 6 (#11)

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] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/gradle-build.yml

@@ -21,7 +21,7 @@ jobs:
       contents: read
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set up JDK 17
         uses: actions/setup-java@v5

.github/workflows/gradle-dependency-submission.yml

@@ -24,7 +24,7 @@ jobs:
       contents: write
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set up JDK 17
         uses: actions/setup-java@v5

.github/workflows/gradle-publish-release.yml

@@ -14,7 +14,7 @@ jobs:
       contents: read
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set up JDK 17
         uses: actions/setup-java@v5

.github/workflows/gradle-publish-snapshot.yml

@@ -26,7 +26,7 @@ jobs:
       should_run: ${{ steps.check.outputs.should_run }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Check if SNAPSHOT publish is applicable
         id: check
@@ -51,7 +51,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set up JDK 17
         uses: actions/setup-java@v5

.github/workflows/validate-next_version.txt.yml

@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Validate next_version.txt file
         env: