Update adjust_bounds by removing iteration

[ehgus]

The adjust_bounds is optimized into a one-line using the floor in base julia. Here is the simple benchmark.

benchamarked julia version : 1.6.1

julia> @time adjust_bounds(90001.0,3.0)
  0.000029 seconds
1.0

julia> @time adjust_bounds_new(90001.0,3.0) # this is the function proposed
  0.000000 seconds
1.0

[jgreener64]

Clear improvement, thanks.