build(deps): bump kotlin.version from 1.4.20 to 1.4.21

Bumps `kotlin.version` from 1.4.20 to 1.4.21.

Updates `kotlin-stdlib` from 1.4.20 to 1.4.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.4.20...v1.4.21)

Updates `kotlin-stdlib-jdk8` from 1.4.20 to 1.4.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.4.20...v1.4.21)

Updates `kotlin-reflect` from 1.4.20 to 1.4.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.4.20...v1.4.21)

Updates `kotlin-maven-plugin` from 1.4.20 to 1.4.21

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

modules/jooby-bom/pom.xml

@@ -65,7 +65,7 @@
   <jsr305.version>3.0.2</jsr305.version>
   <junit.version>5.7.0</junit.version>
   <kafka.version>2.7.0</kafka.version>
-  <kotlin.version>1.4.20</kotlin.version>
+  <kotlin.version>1.4.21</kotlin.version>
   <kotlinx-coroutines-core.version>1.4.1</kotlinx-coroutines-core.version>
   <lettuce.version>6.0.1.RELEASE</lettuce.version>
   <license-maven-plugin.version>3.0</license-maven-plugin.version>

pom.xml

@@ -103,7 +103,7 @@
     <unbescape.version>1.1.6.RELEASE</unbescape.version>
 
     <!-- Kotlin -->
-    <kotlin.version>1.4.20</kotlin.version>
+    <kotlin.version>1.4.21</kotlin.version>
     <kotlinx-coroutines-core.version>1.4.1</kotlinx-coroutines-core.version>
 
     <!-- Test dependencies -->