specify yyyy date format

SignalServiceKit/src/Contacts/ContactDiscoveryService.m

@@ -623,7 +623,7 @@ NSError *ContactDiscoveryServiceErrorMakeWithReason(NSInteger code, NSString *re
     NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
     NSTimeZone *timeZone = [NSTimeZone timeZoneWithName:@"UTC"];
     [dateFormatter setTimeZone:timeZone];
-    [dateFormatter setDateFormat:@"yyy-MM-dd'T'HH:mm:ss.SSSSSS"];
+    [dateFormatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss.SSSSSS"];
 
     // Specify parsing locale
     // from: https://developer.apple.com/library/archive/qa/qa1480/_index.html