remove deprecated property from gradle

Author: ncipollo

gradle.properties

@@ -1,5 +1,4 @@
 kotlin.code.style=official
-kotlin.mpp.enableCompatibilityMetadataVariant=true
 kotlin.js.generate.executable.default=false
 kotlin.native.cacheKind.linuxX64=none
 org.gradle.jvmargs=-Xmx2048m -XX:MaxPermSize=512m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8