Maybe support recaptcha.net
It's unable to visit https://www.google.com/recaptcha in China.For example, people in China can't register Nim Forum because google is banned.
So Maybe can replace this www.google.com with recaptcha.net when detected Country.

My pr in:
https://github.com/euantorano/recaptcha.nim/pull/5

Infos can be found in https://developers.google.com/recaptcha/docs/faq#can-i-use-recaptcha-globally
List below:

Can I use reCAPTCHA globally?
Yes, please use "www.recaptcha.net" in your code in circumstances when "www.google.com" is not accessible.

First, replace <script src="https://www.google.com/recaptcha/api.js" async defer></script> with <script src="https://www.recaptcha.net/recaptcha/api.js" async defer></script>
After that, apply the same to everywhere else that uses "www.google.com/recaptcha/" on your site.