Merge pull request #241 from input-output-hk/coot/io-sim-si-timers
reverted si-timers: round difftime to microseconds in IOSim
reverted si-timers: round difftime to microseconds in IOSim
Reverted only rounding in `io-sim`, but kept the `roundDiffTimeToMicroseconds` in `MonadTimer.SI`.
build(deps): bump actions/cache from 4 to 5