Upgrade to Kotlin 1.3.50

Closes gh-17982

Author: snicoll

spring-boot-project/spring-boot-dependencies/pom.xml

@@ -142,7 +142,7 @@
 		<junit.version>4.12</junit.version>
 		<junit-jupiter.version>5.5.1</junit-jupiter.version>
 		<kafka.version>2.3.0</kafka.version>
-		<kotlin.version>1.3.41</kotlin.version>
+		<kotlin.version>1.3.50</kotlin.version>
 		<kotlin-coroutines.version>1.3.0</kotlin-coroutines.version>
 		<lettuce.version>5.1.8.RELEASE</lettuce.version>
 		<liquibase.version>3.7.0</liquibase.version>