chore(deps): update dependency com.diffplug.spotless:spotless-maven-plugin to v3.9.0

Author: renovate[bot]

topics/testing/code/pom.xml

@@ -153,7 +153,7 @@
             <plugin>
                 <groupId>com.diffplug.spotless</groupId>
                 <artifactId>spotless-maven-plugin</artifactId>
-                <version>3.8.0</version>
+                <version>3.9.0</version>
                 <configuration>
                     <java>
                         <importOrder />