[iOS] Remove unneeded imports

ios/sdk/src/CallKit.m

 #import <UIKit/UIKit.h>
 
 #import <React/RCTBridge.h>
-#import <React/RCTConvert.h>
-#import <React/RCTEventDispatcher.h>
 #import <React/RCTEventEmitter.h>
 #import <React/RCTUtils.h>