ci: adopt gradle/actions/setup-gradle (#180)

Replaces setup-java's coarse gradle cache with the Gradle-recommended
setup-gradle action: finer-grained caching with automatic cleanup and
read-only caches on non-default branches, Gradle wrapper checksum
validation (guarding the Dependabot wrapper-bump stream), and build/
cache job summaries.

Author: ardetrick

.github/workflows/gradle.yml

@@ -26,7 +26,8 @@ jobs:
         with:
           java-version: '21'
           distribution: 'temurin'
-          cache: 'gradle'
+      - name: Set up Gradle
+        uses: gradle/actions/setup-gradle@v6
       - name: Setup ms-playwright cache
         id: setup-ms-playwright-cache
         uses: actions/cache@v6

.github/workflows/upstream-canary.yml

@@ -60,7 +60,8 @@ jobs:
         with:
           java-version: '21'
           distribution: 'temurin'
-          cache: 'gradle'
+      - name: Set up Gradle
+        uses: gradle/actions/setup-gradle@v6
       - name: Setup ms-playwright cache
         id: setup-ms-playwright-cache
         uses: actions/cache@v6