Bump kotlin.version from 1.4.31 to 1.5.20 (#157)

Bumps `kotlin.version` from 1.4.31 to 1.5.20.

Updates `kotlin-stdlib` from 1.4.31 to 1.5.20
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v1.5.20/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.4.31...v1.5.20)

Updates `kotlin-test-junit` from 1.4.31 to 1.5.20
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v1.5.20/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.4.31...v1.5.20)

Updates `kotlin-maven-plugin` from 1.4.31 to 1.5.20

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

pom.xml

@@ -11,7 +11,7 @@
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-        <kotlin.version>1.4.31</kotlin.version>
+        <kotlin.version>1.5.20</kotlin.version>
         <lucene.version>8.5.2</lucene.version>
         <word.version>1.3</word.version>
         <gson.version>2.8.6</gson.version>