github: test on jdk17+

Author: mvysny

.github/workflows/gradle.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest]
-        java: [11, 17, 21]
+        java: [17, 21]
 
     runs-on: ${{ matrix.os }}