update twitter link. twitter.com -> x.com

Author: partev

_config.yml

@@ -57,7 +57,7 @@ external_urls:
   hub_issues: https://github.com/pytorch/hub/issues
   contributing: https://github.com/pytorch/pytorch/blob/master/CONTRIBUTING.md
   hub_template: https://github.com/pytorch/hub/blob/master/docs/template.md
-  twitter: https://twitter.com/pytorch
+  twitter: https://x.com/pytorch
   facebook: https://www.facebook.com/pytorch
   slack: https://join.slack.com/t/pytorch/shared_invite/zt-2j2la612p-miUinTTaxXczKOJw48poHA
   wechat: https://pytorch.org/wechat