chore(deps): update actions/setup-java action to v2 (#451)

See https://github.com/actions/setup-java/blob/main/docs/switching-to-v2.md
for details.

Author: renovate-bot

.github/workflows/tests.yml

@@ -23,8 +23,9 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v2
       - name: Set up JDK 1.8
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
-          java-version: 1.8
+          distribution: 'zulu'
+          java-version: '8'
       - name: Get Maven checkstyle report
-        run: mvn -B checkstyle:check
+        run: mvn -B checkstyle:check