chore(deps): Update plugin spotless to v7

Author: renovate[bot]

gradle/libs.versions.toml

@@ -25,4 +25,4 @@ indra-crossdoc = { id = "net.kyori.indra.crossdoc", version.ref = "indra" }
 indra-licenser-spotless = { id = "net.kyori.indra.licenser.spotless", version.ref = "indra" }
 indra-publishing-sonatype = { id = "net.kyori.indra.publishing.sonatype", version.ref = "indra" }
 nexusPublish = { id = "io.github.gradle-nexus.publish-plugin", version = "2.0.0-rc-1" }
-spotless = "com.diffplug.spotless:6.21.0"
+spotless = "com.diffplug.spotless:7.0.3"