Build(deps): Bump com.diffplug.spotless from 6.12.0 to 6.13.0

Dependabot couldn't find the original pull request head commit, 10076aeed8cee158e02965ed13b423e9a47208d8.

app/build.gradle

@@ -17,7 +17,7 @@ buildscript {
 }
 
 plugins {
-    id "com.diffplug.spotless" version "6.12.0"
+    id "com.diffplug.spotless" version "6.13.0"
 }
 
 apply plugin: 'com.android.application'