Fix webservice authentication bug caused by pylint streak

solvable/src/webservice/user_ops.py

@@ -27,12 +27,10 @@ class UserOps:
             User.username == self.username
         ).first()
 
-        passw_is_correct = PasswordHasher.verify(
-            self.password,
-            user.passwordhash
-        )
-
-        if not user or not passw_is_correct:
+        if not user or not PasswordHasher.verify(
+                self.password,
+                user.passwordhash
+        ):
             self.log(f'Invalid credentials for user "{self.username}"!')
             raise InvalidCredentialsError