2fa can't be activated on app.pullrequest.com

How it was found

Summary: Hello Team, Since you are using deprecated google chart API service (which doesn't work now) for generating 2fa qr code image, users cannot setup 2fa for securing account.

Steps To Reproduce

1. Log into https://app.pullrequest.com
2. Go to "User Settings" -> "Security" -> "Two-Factor Authentication"
3. You cannot when you try enabling it

Impact

I understand it is kinda technical bug. But I decided to report as it literally affects all existing and new users by not allowing them to secure their account.