Revert "Bump checkstyle from 9.3 to 10.0 (#813)" (#814)

This reverts commit 49dccf6.

Author: majst01

pom.xml

@@ -216,7 +216,7 @@
           <dependency>
             <groupId>com.puppycrawl.tools</groupId>
             <artifactId>checkstyle</artifactId>
-            <version>10.0</version>
+            <version>9.3</version>
           </dependency>
         </dependencies>
         <configuration>