Fix scrollbar hide

[ppizarror]

• Improve scrollbar hide/show adding new force param.

[codecov]

Codecov Report

Merging #397 (b6257ea) into master (41d3d50) will increase coverage by 0.00%.
The diff coverage is 95.40%.

@@           Coverage Diff           @@
##           master     #397   +/-   ##
=======================================
  Coverage   97.22%   97.23%           
=======================================
  Files          48       48           
  Lines       12058    12096   +38     
=======================================
+ Hits        11723    11761   +38     
  Misses        335      335           

Impacted Files	Coverage Δ
pygame_menu/_scrollarea.py	99.28% <94.36%> (+0.03%)	⬆️
pygame_menu/locals.py	100.00% <100.00%> (ø)
pygame_menu/widgets/widget/scrollbar.py	95.28% <100.00%> (+0.21%)	⬆️

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