* para scheduler: fix  division

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

* Update runtime/parachains/src/scheduler.rs

Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>

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Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>