User label url

Each label also has a URL which is used for learning more about the
label. While there are more label descriptions than label URLs the URLs
do seem to group language variants of the same label. For example
https://help.twitter.com/rules-and-policies/state-affiliated-china is
used for all of the following label descriptions:

* Média affilié à un État, Chine
* China state-affiliated media
* 中国官方媒体
* Çin devletine bağlı medya
* China government official

In some analysis contexts it could be useful to group these together.

snscrape/modules/twitter.py

@@ -137,6 +137,7 @@ class User(snscrape.base.Entity):
 	profileImageUrl: typing.Optional[str] = None
 	profileBannerUrl: typing.Optional[str] = None
 	label: typing.Optional[str] = None
+	labelUrl: typing.Optional[str] = None
 
 	@property
 	def url(self):
@@ -460,6 +461,7 @@ class TwitterAPIScraper(snscrape.base.Scraper):
 		kwargs['profileBannerUrl'] = user.get('profile_banner_url')
 		if 'label' in user['ext']['highlightedLabel']['r']['ok']:
 			kwargs['label'] = user['ext']['highlightedLabel']['r']['ok']['label']['description']
+			kwargs['labelUrl'] = user['ext']['highlightedLabel']['r']['ok']['label']['url']['url']
 		
 		return User(**kwargs)