fix: allow colors as array

[LovelyAndy]

There are some charts where I need to use different label colors per label.
Using a string[] for the label color seems to work, but TS won't allow it.
This PR fixes the types to allow that.

[etimberg]

Where specifically are you passing the colors as an array? I don't think all spots that accept colours accept arrays of colours, so I'm not sure this change is the correct one to make.

[LeeLenaleee]

This will break some parts since in the typing some things are defined as an array of collors like here: https://github.com/chartjs/Chart.js/blob/master/types/index.esm.d.ts#L2822

Which will make a double array valid which isn't supported

[LovelyAndy]

@LeeLenaleee Thank you very much. Updated the PR to make the change under TickOptions!

[LeeLenaleee]

Make it more in line with the other lines that do this:
https://github.com/chartjs/Chart.js/blob/master/types/index.esm.d.ts#L2822
https://github.com/chartjs/Chart.js/blob/master/types/index.esm.d.ts#L2859

[LovelyAndy]

@kurkle Thanks! Updated as per your suggestion.