Upgrade com.spotify.fmt:fmt-maven-plugin 2.20 -> 2.21.1

See:
- https://github.com/spotify/fmt-maven-plugin/releases/tag/2.21.1
- https://github.com/spotify/fmt-maven-plugin/releases/tag/2.21

pom.xml

@@ -524,7 +524,7 @@
                 <plugin>
                     <groupId>com.spotify.fmt</groupId>
                     <artifactId>fmt-maven-plugin</artifactId>
-                    <version>2.20</version>
+                    <version>2.21.1</version>
                     <configuration>
                         <additionalSourceDirectories>
                             <additionalSourceDirectory>${basedir}/src/test/resources</additionalSourceDirectory>