Migrate build to Gradle 9 (#935) #29

Job	Run time
Build scip-java CLI	4m 34s
gradle-java21-readiness	2m 46s
maven-java17-spring-boot	2m 36s
gradle-kotlin-flowext	3m 30s
gradle-mixed-okio-jmh	3m 13s
maven-kotlin-json-kotlin-maven	1m 34s
gradle-kotlin-okio	4m 29s
bazel-java-examples	2m 33s
	25m 15s

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