deps: revert google-java-format to 1.7 (#453)

Fixes #452 .

(This revert would fix the problem but when RenovateBot create a pull request we'll be forgetting about the problem.)

Author: suztomo

pom.xml

@@ -225,7 +225,7 @@
             <dependency>
               <groupId>com.google.googlejavaformat</groupId>
               <artifactId>google-java-format</artifactId>
-              <version>1.15.0</version>
+              <version>1.7</version>
             </dependency>
           </dependencies>
         </plugin>