Update dependency com.github.spotbugs.snom:spotbugs-gradle-plugin to v6

Author: renovate[bot]

build.gradle

@@ -9,7 +9,7 @@ buildscript {
         }
     }
     dependencies {
-        classpath "com.github.spotbugs.snom:spotbugs-gradle-plugin:5.2.5"
+        classpath "com.github.spotbugs.snom:spotbugs-gradle-plugin:6.0.21"
     }
 }