Bump default cleanthat 2.8 -> 2.13.

Author: nedtwigg

lib/src/main/java/com/diffplug/spotless/java/CleanthatJavaStep.java

@@ -40,7 +40,7 @@ public final class CleanthatJavaStep {
 	private static final String MAVEN_COORDINATE = "io.github.solven-eu.cleanthat:java";
 
 	// CleanThat changelog is available at https://github.com/solven-eu/cleanthat/blob/master/CHANGES.MD
-	private static final Jvm.Support<String> JVM_SUPPORT = Jvm.<String> support(NAME).add(11, "2.8");
+	private static final Jvm.Support<String> JVM_SUPPORT = Jvm.<String> support(NAME).add(11, "2.13");
 
 	// prevent direct instantiation
 	private CleanthatJavaStep() {}