[Auth UI] Should use number keyboard for verification code

[keithtkl]

Should use number keyboard for verification code as it is a 4-digit number

• Skygear Server Date/Version: Not sure
• Application Platform: Tested on Rees

Expected Results

Display number keyboard when press on the verification code field

Actual Results

Text keyboard has been shown when focus on the field

Steps to reproduce

1. Signup / Login with email address or phone number
2. On the verification page, click on the code field will see the text keyboard

[louischan-oursky]

Use <input type="tel">. <input type="number"> adds spinner which is very confusing.