chore(cleanup): Remove Serializable from GroupMetaDataDto [2.6.x] (#6369)

* Remove Serializable from GroupMetaDataDto

* Update GroupMetaDataDto.java

Author: EricWittmann

app/src/main/java/io/apicurio/registry/storage/dto/GroupMetaDataDto.java

@@ -21,7 +21,6 @@
 import lombok.EqualsAndHashCode;
 import lombok.ToString;
 
-import java.io.Serializable;
 import java.util.Map;
 
 /**
@@ -31,7 +30,7 @@
 @Builder
 @EqualsAndHashCode
 @ToString
-public class GroupMetaDataDto implements Serializable {
+public class GroupMetaDataDto {
 
     private static final long serialVersionUID = -9015518049780762742L;