Extend new_algo.salt1 to fix edit_2fa (#1072)

The salt1 that is sent to the server requires an additional 32 bytes
of random data. It's easy to miss this requirement from reading the 
tdesktop source, because this extension is done in a function called
`ValidateNewCloudPasswordAlgo`.

https://github.com/telegramdesktop/tdesktop/blob/2e5a0e056cdb40d61d487c6062bffe1a835f
6ddd/Telegram/SourceFiles/core/core_cloud_password.cpp#L210-L211

telethon/client/auth.py

@@ -467,6 +467,7 @@ class AuthMethods(MessageParseMethods, UserMethods):
             return False
 
         pwd = await self(functions.account.GetPasswordRequest())
+        pwd.new_algo.salt1 += os.urandom(32)
         assert isinstance(pwd, types.account.Password)
         if not pwd.has_password and current_password:
             current_password = None