Update Spotless plugin.

Change-Id: I063e560850ed7637d1dd3c4445a652a8ba777e72
diff --git a/gradle.properties b/gradle.properties
index 31b42c2..63b5f33 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -12,7 +12,7 @@
 #quarkusPluginVersion = 999-SNAPSHOT
 
 dockerPluginVersion = 6.3.0
-spotlessPluginVersion = 3.27.2
+spotlessPluginVersion = 3.28.0
 versionsPluginVersion = 0.28.0
 useLatestVersionsPluginVersion = 0.2.13