Update postgres row where condition is from another table
I believe this can be solved relatively quickly, by adding a FROM clause to your UPDATE, and adding an additional equality condition, namely, adding user_info.user_login = user_contacts.user_login.    

UPDATE user_info SET password = '$2a$11$fwea...IEI' 
FROM user_contacts
WHERE user_info.user_login = user_contacts.user_login
AND user_contacts.email = 'ad@...com';


This will almost certainly do what you are asking.

Refer to the PostgreSQL Documentation on UPDATE for more info.