Magiclysm: update mana regen less often

[KorGgenT]

this allows for larger chunks of mana to be regenerated at a time

Summary

SUMMARY: Bugfixes "make mana regen less often in larger chunks"

Purpose of change

Fixes #31271

Describe the solution

With the time change, 10 turns became a lot shorter, so the calculations cause mana regen to be 0 more often than not with mana regen. I increase it from 10 turns to 3 minutes, so with very bad mana regen you're likely to have at least 1 regen every 3 minutes.

[jbytheway]

If this is because of rounding, have you considered using roll_remainder?