fix: Discord oauth2 missing "code_challenge" (#1440)

* fix: Discord oauth2 missing "code_challenge"

* Update discord.ts

Author: Intevel

src/providers/discord.ts

@@ -17,7 +17,10 @@ export function discord(
       authorization: 'https://discord.com/api/oauth2/authorize',
       token: 'https://discord.com/api/oauth2/token',
       userInfo: 'https://discord.com/api/users/@me'
+      //   logout: 'https://discord.com/api/oauth2/token/revoke' //TODO: add post method, because discord using the post method to logout
     },
+    grantType: 'authorization_code',
+    codeChallengeMethod: 'S256',
     scope: ['identify', 'email']
   }