Update dependency com.diffplug.spotless to v8.9.0 #177

Job	Run time
Build scip-java CLI	4m 31s
gradle-kotlin-kotlinconf-app	9m 30s
maven-java25-demo	1m 47s
gradle-java21-readiness	1m 48s
gradle-mixed-kotlinpoet	4m 30s
maven-java17-spring-boot	2m 54s
bazel-java-examples	1m 43s
gradle-kotlin-kotlinpoet	3m 56s
maven-kotlin-json-kotlin-maven	2m 24s
Repository indexing pass	3s
	33m 6s

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