fix: make get_colors return wrt to color_overrides

[agronskiy]

The issue

As a user of the theme, I want color_overrides, which I have passed during the setup, to have effect on get_colors elsewhere. Currently, they only have effect during the initialization of the theme.

The fix

Add deep table merge into get_colors.

Tests

Tested locally by importing colors in different other places of my setup.

[agronskiy]

Hey @Mofiqul, thanks for a great plugin. While playing with it and wanting to extend couple of other highlight groups in a consistent way (== by using local c = require("vscode.colors").get_colors()) I realized that it returned unchanged table, despite me having color_overrides in init. This fixes it.

I hope this is the desired behavior.

[Mofiqul]

Looks good 👍