warnings output when `marker-[start|mid|end]` set to `none`

[jnqnfe]

Using version 0.45.1-6 on Debian.

When converting an svg like the following, in which a marker is used on some elements but suppressed on others by using marker-start:none, marker-mid:none or marker-end:none, resvg outputs a bunch of parser warnings to the console about use of the value none with these properties. It does not do so for marker:none.

Console output for the above file:

Warning (in usvg::parser::svgtree:289): Failed to parse marker-start value: 'none'.
Warning (in usvg::parser::svgtree:289): Failed to parse marker-mid value: 'none'.
Warning (in usvg::parser::svgtree:289): Failed to parse marker-end value: 'none'.
Warning (in usvg::parser::svgtree:289): Failed to parse marker-start value: 'none'.
Warning (in usvg::parser::svgtree:289): Failed to parse marker-mid value: 'none'.
Warning (in usvg::parser::svgtree:289): Failed to parse marker-end value: 'none'.

[LaurenzV]

This should already be fixed on newest main: #994