Update Java version to 17 in workflow.

Author: yegor256

.github/workflows/mvn.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-24.04, windows-2022, macos-15]
-        java: [11, 21]
+        java: [17, 21]
     steps:
       - uses: actions/checkout@v6
       - uses: actions/setup-java@v5