17304 view time entries permission not respected on wp spent hours

[``* `#17304` View time entries permission not respected for work package's spent hours attribute``](https://community.openproject.org/work_packages/17304)
Unused method argument - `usr`. If it's necessary, use `_` or `_usr` as an argument name to indicate that it won't be used. You can also write as `spent_hours(*)` if you want the method to accept any arguments but don't care about them.