chore: downgrade build to Java 24 and upgrade kotlin 2.2.20

Motivation:

Kotlin still doesn't support Java 25.
Downgrading build to latest supported version.

Author: slandelle

.github/workflows/ci.yaml

@@ -15,7 +15,7 @@ jobs:
       - uses: actions/setup-java@v5
         with:
           distribution: "zulu"
-          java-version: "25"
+          java-version: "24"
       - name: Cache Maven packages
         uses: actions/cache@v4
         with:

src/it/multilanguage-kotlinscala/pom.xml

@@ -25,7 +25,7 @@
       <plugin>
         <groupId>org.jetbrains.kotlin</groupId>
         <artifactId>kotlin-maven-plugin</artifactId>
-        <version>1.9.23</version>
+        <version>2.2.20</version>
         <executions>
           <execution>
             <id>compile</id>