Lib unnecessarily requires @babel/preset-env? #227

It appears that this library requires @babel/preset-env due to its use of Numeric Separators.

I was wondering if it's possible to not use the underscore in L257

for (const [i, element] of rgb.entries()) {
    const chan = element / 255;
    lum[i] = (chan <= 0.039_28) ? chan / 12.92 : ((chan + 0.055) / 1.055) ** 2.4;
}

Changing this would mean projects don't need to transpile it.

If agreed, I am happy to open a PR :)