Bump com.diffplug.spotless from 7.1.0 to 7.2.1 (#28)

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Bumps com.diffplug.spotless from 7.1.0 to 7.2.1.


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build.gradle

@@ -2,7 +2,7 @@ plugins {
     id 'java'
 
     id 'checkstyle'
-    id 'com.diffplug.spotless' version '7.1.0'
+    id 'com.diffplug.spotless' version '7.2.1'
 }