Migrate build to Gradle 9 #20

Job	Run time
Build scip-java CLI	4m 48s
maven-kotlin-json-kotlin-maven	3m 8s
gradle-kotlin-okio	4m 46s
gradle-java21-readiness	3m 7s
maven-java17-spring-boot	3m 8s
bazel-java-examples	1m 33s
gradle-kotlin-flowext	3m 5s
gradle-mixed-okio-jmh	4m 42s
	28m 17s

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