remove unused code

SignalServiceKit/src/Account/TSPreKeyManager.h

@@ -4,19 +4,6 @@
 
 #import "TSAccountManager.h"
 
-typedef NS_ENUM(NSInteger, RefreshPreKeysMode) {
-    // Refresh the signed prekey AND the one-time prekeys.
-    RefreshPreKeysMode_SignedAndOneTime,
-    // Only refresh the signed prekey, which should happen around every 48 hours.
-    //
-    // Most users will refresh their signed prekeys much more often than their
-    // one-time prekeys, so we use a "signed only" mode to avoid updating the
-    // one-time keys in this case.
-    //
-    // We do not need a "one-time only" mode.
-    RefreshPreKeysMode_SignedOnly,
-};
-
 @interface TSPreKeyManager : NSObject
 
 #pragma mark - State Tracking

SignalServiceKit/src/Account/TSPreKeyManager.m

@@ -8,7 +8,6 @@
 #import "NSURLSessionDataTask+StatusCode.h"
 #import "OWSIdentityManager.h"
 #import "OWSPrimaryStorage+SignedPreKeyStore.h"
-#import "OWSRequestFactory.h"
 #import "TSNetworkManager.h"
 #import "TSStorageHeaders.h"
 #import <SignalServiceKit/SignalServiceKit-Swift.h>