swapped to java 11

Server/build.gradle

@@ -11,7 +11,7 @@ compileJava {
 
 compileKotlin {
     kotlinOptions {
-        jvmTarget = JavaVersion.VERSION_1_8
+        jvmTarget = JavaVersion.VERSION_11
         freeCompilerArgs += '-XXLanguage:-NewInference'
     }
 }
@@ -47,4 +47,4 @@ jar {
         attributes 'Main-Class': 'rs09.Server'
     }
     from { configurations.compileClasspath.collect { it.isDirectory() ? it : zipTree(it) } }
-}
+}