Use Kotlin 1.4.21 by default

See https://nvd.nist.gov/vuln/detail/CVE-2020-29582

Author: pmwmedia

pom.xml

@@ -88,7 +88,7 @@
 		<jboss-logging.version>3.4.2.Final</jboss-logging.version>
 		<jmh.version>1.33</jmh.version>
 		<junit.version>4.13.2</junit.version>
-		<kotlin.version>1.3.72</kotlin.version>
+		<kotlin.version>1.4.21</kotlin.version>
 		<lifecycle-mapping.version>1.0.0</lifecycle-mapping.version>
 		<mockk.version>1.12.1</mockk.version>
 		<powermock.version>2.0.9</powermock.version>