Invalid reset of `_win_cache` for statuslines

[jonatan-branting]

Due to a typo in the code, the _win_cache attribute is not properly reset if update is a function.

heirline.nvim/lua/heirline/statusline.lua

Line 270 in 8a8d661

self._win_cahe = nil

(note the win_cahe spelling!)

This (unsurprisingly) causes update to not function at all if it is a function.

[rebelot]

Thanks a lot for debugging this, sorry for the inconvenience. Fixing ASAP.