Update Checkstyles to 8.18 for security fix

Crim · Crim · commit f1aef1bc2368 · 2019-03-23T09:57:21.000+09:00
diff --git a/pom.xml b/pom.xml
@@ -275,7 +275,7 @@
                         <dependency>
                             <groupId>com.puppycrawl.tools</groupId>
                             <artifactId>checkstyle</artifactId>
-                            <version>8.12</version>
+                            <version>8.18</version>
                         </dependency>
                     </dependencies>
                 </plugin>
