Bump GitHub CI build from JDK 17-ea to 17, remove 16

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

.github/workflows/maven.yml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java: [ 8, 11, 16, 17-ea ]
+        java: [ 8, 11, 17 ]
     steps:
       - uses: actions/checkout@v2