Downgrade Java version for the org.yarp project to 8+

org.yarp source code should be compatible with Java 8 because JRuby supports this version

Author: andrykonchin

mx.truffleruby/suite.py

@@ -131,7 +131,7 @@
             "sourceDirs": ["java"],
             "jniHeaders": True,
             "jacoco": "include",
-            "javaCompliance": "17+",
+            "javaCompliance": "8+",
             "workingSets": "TruffleRuby",
             "license": ["MIT"],
         },