Revert "Upgrade to Kotlin 1.4 M2" for spring-r2dbc

spring-r2dbc/spring-r2dbc.gradle

@@ -2,12 +2,6 @@ description = "Spring R2DBC"
 
 apply plugin: "kotlin"
 
-// Workaround for https://youtrack.jetbrains.com/issue/KT-39610
-configurations["optional"].attributes.attribute(
-	org.gradle.api.attributes.Usage.USAGE_ATTRIBUTE,
-	objects.named(Usage.class, "java-runtime")
-)
-
 dependencies {
 	compile(project(":spring-beans"))
 	compile(project(":spring-core"))