Bump kotlin.version from 2.0.20 to 2.0.21

Author: dependabot[bot]

pom-central.xml

@@ -27,7 +27,7 @@
   </scm>
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <kotlin.version>2.0.20</kotlin.version>
+    <kotlin.version>2.0.21</kotlin.version>
   </properties>
   <ciManagement>
     <system>GitHub Actions</system>
@@ -173,7 +173,7 @@
       <plugin>
         <groupId>org.jetbrains.dokka</groupId>
         <artifactId>dokka-maven-plugin</artifactId>
-        <version>1.9.20</version>
+        <version>2.0.0-Beta</version>
         <configuration>
           <jdkVersion>11</jdkVersion>
         </configuration>

pom.xml

@@ -27,7 +27,7 @@
   </scm>
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <kotlin.version>2.0.20</kotlin.version>
+    <kotlin.version>2.0.21</kotlin.version>
   </properties>
   <ciManagement>
     <system>GitHub Actions</system>