[CI] Use built-in caching from setup-java action

https://github.com/actions/setup-java#caching-packages-dependencies:
> `setup-java` action has a built-in functionality for caching and restoring dependencies. It uses actions/cache under hood for caching dependencies but requires less configuration settings.

.github/workflows/build.yml

@@ -19,21 +19,12 @@ jobs:
       - name: Validate Gradle Wrapper
         uses: gradle/wrapper-validation-action@v1
 
-      - name: Generate cache key
-        run: ./.github/workflows/checksum.sh checksum.txt
-
-      - uses: actions/cache@v2
-        with:
-          path: ~/.gradle/caches
-          key: ${{ runner.os }}-gradle-${{ hashFiles('checksum.txt') }}
-          restore-keys: |
-            ${{ runner.os }}-gradle-
-
       - name: Configure JDK
         uses: actions/setup-java@v3
         with:
           distribution: 'zulu'
           java-version: '18'
+          cache: 'gradle'
 
       - name: Test
         run: ./gradlew build check --stacktrace -PkotlinTestMode=${{ matrix.kotlin-test-mode }}