add geantyref to fix and simplify generic Type parsing.

Also switch to java 23 to avoid conflicts and issues.

wrapper/javacord/build.gradle.kts

@@ -29,7 +29,7 @@ dependencies {
 // Apply a specific Java toolchain to ease working on different environments.
 java {
     toolchain {
-        languageVersion = JavaLanguageVersion.of(21)
+        languageVersion = JavaLanguageVersion.of(23)
     }
 }