Upgrade librsvg to v2.59.0
This MR upgrades librsvg to v2.59.0 (non-beta). I need it because tiny-dfr depends on librsvg, and since a non-beta version was released there's no need to use allow_prerelease_deps = true
. However, I'd like to check first with @werdahias that this is alright.
P.S.: @werdahias, could you sponsor the upload of both librsvg and tiny-dfr while you're at it? Thank you.