Gradle plugin is not compatible with upcoming Gradle 9.x

[rpalcolea]

Hi folks!

I noticed that trying to use the gradle plugin fails in Gradle 9.0.0-rc-3 fails with:

Caused by: java.lang.NoClassDefFoundError: groovy/util/XmlNodePrinter
        at com.palantir.javaformat.gradle.XmlUtils.updateIdeaXmlFile(XmlUtils.java:51)
        at com.palantir.javaformat.gradle.UpdatePalantirJavaFormatIdeaXmlFile.updateXml(UpdatePalantirJavaFormatIdeaXmlFile.java:60)
        at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:125)

This makes sense as groovy/util/XmlNodePrinter and other classes were deprecated back in Groovy 3.x and removed in 4.x in favor of groovy.xml package.

I think moving to newer packages is sufficient enough