[FIX] users_ldap_populate: Decode login information

When iterating through the users from LDAP, if the login information
is read in bytes, passing the value in bytes to the psycopg2 library
doesn't work, failing with this error:

```
psycopg2.errors.UndefinedFunction: operator does not exist: text = bytea
LINE 1: SELECT id FROM res_users WHERE lower(login)='...
```

so we need to decode the result before to get a pure string.

TT56992

Author: pedrobaeza

users_ldap_populate/models/users_ldap.py

@@ -66,6 +66,8 @@ def action_populate(self):
             results = self._get_ldap_entry_dicts(conf)
             for result in results:
                 login = result[1][login_attr][0].lower().strip()
+                if isinstance(login, bytes):
+                    login = login.decode()
                 user_id = None
                 try:
                     user_id = self.with_context(