Remove duplicate and invalid stop elements

[yisibl]

<svg viewBox="0 0 1024 1024" xmlns="http://www.w3.org/2000/svg">
    <defs>
        <linearGradient id="lg1">
            <stop offset="-1" stop-color="yellow" />
            <stop offset="0" stop-color="yellow" />
            <stop offset="0.5" stop-color="green" />
            <stop offset="0.5" stop-color="green" />
            <stop offset="1" stop-color="yellow" />
            <stop offset="10" stop-color="yellow" />
        </linearGradient>
    </defs>
    <circle fill="url(#lg1)" cx="50" cy="50" r="45" />
</svg>

offset="-1" and 10 Is an invalid value, currently picosvg will cause an error.
offset="0.5" There are two duplicates and one needs to be deleted, otherwise there will be redundant in the generated font file.

Do we consider introducing an svg compression tool to handle more edge cases?

e.g.
svgcleaner: https://github.com/RazrFalcon/svgcleaner/blob/master/docs/svgcleaner.adoc#remove-title-element
scour: scour-project/scour#102

<ColorLine>
    <Extend value="pad" />
    <!-- StopCount=4 -->
    <ColorStop index="0">
        <StopOffset value="0.0" />
        <Color>
            <PaletteIndex value="1" />
            <Alpha value="1.0" />
        </Color>
    </ColorStop>
    <ColorStop index="1">
        <StopOffset value="0.5" />
        <Color>
            <PaletteIndex value="0" />
            <Alpha value="1.0" />
        </Color>
    </ColorStop>
    <ColorStop index="2">
        <StopOffset value="0.5" />
        <Color>
            <PaletteIndex value="0" />
            <Alpha value="1.0" />
        </Color>
    </ColorStop>
    <ColorStop index="3">
        <StopOffset value="1.0" />
        <Color>
            <PaletteIndex value="1" />
            <Alpha value="1.0" />
        </Color>
    </ColorStop>
</ColorLine>