refactor: remove obsolete class (planning#2016)

client/src/main/java/dev/fitko/fitconnect/api/domain/zbp/state/SenderName.java

-package dev.fitko.fitconnect.api.domain.zbp.state;
-
-import com.fasterxml.jackson.annotation.JsonProperty;
-import lombok.Value;
-
-@Value
-public class SenderName {
-    @JsonProperty("de")
-    String senderName;
-}