update check/colorfont_tables criteria

[felipesanches]

Today @rsheeter said:

@anthrotype pointed out that I've oversimplified this and it would be OK to nuance the rule to say that any of the following states are OK:

1. Has none of {COLR, SVG} (is not color)
2. Has only COLRv0 (somewhat broadly supported, https://caniuse.com/colr)
3. Has COLRv1 and SVG

Any other state is invalid, in particular COLRv0 + SVG should fail.

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