fix: nvim-window-picker buftype rules

[rapan931]

quickfix window filetype is qf,
quickfix window buftype is quickfix,
so move to buftype.

thanks.

[codecov]

Codecov Report

Merging #570 (bf4cb52) into main (168826f) will decrease coverage by 0.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #570      +/-   ##
==========================================
- Coverage   50.62%   50.56%   -0.07%     
==========================================
  Files          47       47              
  Lines        6040     6040              
==========================================
- Hits         3058     3054       -4     
- Misses       2982     2986       +4     

Impacted Files	Coverage Δ
lua/neo-tree/sources/filesystem/init.lua	64.40% <0.00%> (-1.70%)	⬇️

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