chore(deps): bump gradle/actions from 4 to 6 (#16)

Bumps [gradle/actions](https://github.com/gradle/actions) from 4 to 6.
- [Release notes](https://github.com/gradle/actions/releases)
- [Commits](gradle/actions@v4...v6)

---
updated-dependencies:
- dependency-name: gradle/actions
  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/ci.yml

@@ -50,7 +50,7 @@ jobs:
           cache: gradle
 
       - name: Validate Gradle wrapper
-        uses: gradle/actions/wrapper-validation@v4
+        uses: gradle/actions/wrapper-validation@v6
 
       - name: Check formatting (Spotless)
         if: ${{ matrix.jdk == '21' }}

.github/workflows/pitest-nightly.yml

@@ -22,7 +22,7 @@ jobs:
           distribution: temurin
           java-version: "21"
 
-      - uses: gradle/actions/setup-gradle@v4
+      - uses: gradle/actions/setup-gradle@v6
 
       - name: Run PIT mutation analysis
         run: ./gradlew :${{ matrix.module }}:pitest --no-daemon --stacktrace

.github/workflows/release.yml

@@ -31,7 +31,7 @@ jobs:
           distribution: temurin
           java-version: "21"
 
-      - uses: gradle/actions/setup-gradle@v4
+      - uses: gradle/actions/setup-gradle@v6
 
       - name: Configure git for tagging
         run: |