Bump kotlin.version from 1.4.20 to 1.4.21 (#638)

Bumps `kotlin.version` from 1.4.20 to 1.4.21.

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-compiler-embeddable` 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

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

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Peter Trifanov <[email protected]>

diktat-gradle-plugin/build.gradle.kts

@@ -3,7 +3,7 @@ import org.gradle.nativeplatform.platform.internal.DefaultNativePlatform.getCurr
 
 plugins {
     `java-gradle-plugin`
-    kotlin("jvm") version "1.4.20"
+    kotlin("jvm") version "1.4.21"
     jacoco
     id("pl.droidsonroids.jacoco.testkit") version "1.0.7"
 }
@@ -119,4 +119,4 @@ tasks.jacocoTestReport {
         // xml report is used by codecov
         xml.isEnabled = true
     }
-}
+}

pom.xml

@@ -42,7 +42,7 @@
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <kotlin.version>1.4.20</kotlin.version>
+        <kotlin.version>1.4.21</kotlin.version>
         <kotlin.compiler.incremental>true</kotlin.compiler.incremental>
         <kotlinx.serialization.version>1.0.1</kotlinx.serialization.version>
         <ktlint.version>0.39.0</ktlint.version>