Building PRs also on JDK 17 (#1070)

.github/workflows/maven-package.yml

diff --git a/.github/workflows/maven-package.yml b/.github/workflows/maven-package.yml
index f61fe40..280c93a 100644
--- a/.github/workflows/maven-package.yml
+++ b/.github/workflows/maven-package.yml
@@ -11,13 +11,16 @@
   build:
 
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: [ '11', '17' ]
 
     steps:
     - uses: actions/checkout@v2
-    - name: Set up JDK 11
+    - name: Set up JDK ${{ matrix.java }}
       uses: actions/setup-java@v2
       with:
-        java-version: '11'
+        java-version: ${{ matrix.java }}
         distribution: 'temurin'
     - name: Build with Maven
       run: mvn -B verify