chore(deps): update plugin com.diffplug.spotless to v8.4.0 (#7033)

This PR contains the following updates:

| Package | Change |
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|---|---|---|---|
| com.diffplug.spotless | `8.1.0` → `8.4.0` |
![age](https://developer.mend.io/api/mc/badges/age/maven/com.diffplug.spotless:com.diffplug.spotless.gradle.plugin/8.4.0?slim=true)
|
![confidence](https://developer.mend.io/api/mc/badges/confidence/maven/com.diffplug.spotless:com.diffplug.spotless.gradle.plugin/8.1.0/8.4.0?slim=true)
|

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java/build.gradle.kts

@@ -4,7 +4,7 @@
 import net.ltgt.gradle.errorprone.errorprone
 
 plugins {
-    id("com.diffplug.spotless") version "8.1.0"
+    id("com.diffplug.spotless") version "8.4.0"
     id("com.palantir.consistent-versions") version "3.7.0"
     id("com.palantir.git-version") version "5.0.0"
     id("net.ltgt.errorprone") version "5.1.0" apply false