Switch JDK provider to temurin.

AdoptJDK is marked as deprecated and replaced by Eclipse Temurin.

Author: uhafner

.github/workflows/ci.yml

@@ -21,7 +21,7 @@ jobs:
     - name: Set up JDK 11
       uses: actions/setup-java@v2
       with:
-        distribution: 'adopt'
+        distribution: 'temurin'
         java-version: '11'
         check-latest: true
     - name: Cache local Maven repository