vf_scale: param0 and param1 flooring decimals

[Mugnum]

Summary of the bug:

When using scale filter with bicubic algorithm, the param0 and param1 values are floored.
For example, when inputting -param0 1.67, it behaves as if I entered -param0 1.00.

Here's a demonstration of resulting files using utility Resample Scope:
1) ​https://imgur.com/a/IRVtRqI vf_scale -- only integers work
2) ​https://imgur.com/a/1oyoptU vf_scale_cuda -- decimals work, however filter has only 1 parameter

How to reproduce:

ffmpeg -i pl.png 
  -vf "scale=300:300:flags=bicubic:param0=0.33:param1=2/3" 0.png
  -vf "scale=300:300:flags=bicubic:param0=0.99:param1=5/6" 1.png
  -vf "scale=300:300:flags=bicubic:param0=1.00:param1=1"   2.png
ffmpeg version n4.4.1-2-gcc33e73618-20211219 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 11.2.0 (crosstool-NG 1.24.0.498_5075e1f)