MINOR: formatting fix on UpdateRaftVoterRequest class declaration (apache#22010)

Trivial PR just to fix a "wrong" formatting of the
`UpdateRaftVoterRequest` class declaration.

Reviewers: Ken Huang <s7133700@gmail.com>, Chia-Ping Tsai
 <chia7712@gmail.com>

Author: ppatierno

clients/src/main/java/org/apache/kafka/common/requests/UpdateRaftVoterRequest.java

@@ -23,7 +23,7 @@
 import org.apache.kafka.common.protocol.Errors;
 import org.apache.kafka.common.protocol.Readable;
 
-public class    UpdateRaftVoterRequest extends AbstractRequest {
+public class UpdateRaftVoterRequest extends AbstractRequest {
     public static class Builder extends AbstractRequest.Builder<UpdateRaftVoterRequest> {
         private final UpdateRaftVoterRequestData data;