Bump JVM target back to 11

Author: fwcd

gradle.properties

@@ -2,4 +2,4 @@ projectVersion=1.3.0
 kotlinVersion=1.6.10
 exposedVersion=0.37.3
 lsp4jVersion=0.12.0
-javaVersion=8
+javaVersion=11

server/build.gradle

@@ -72,7 +72,7 @@ applicationDistribution.into('bin') {
 
 tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
     kotlinOptions {
-        jvmTarget = "1.8"
+        jvmTarget = "11"
     }
 }