Link fixes

[Shaun Walbridge]

Currently, the releases page [1] has LATEST-pixman-0.42.2 listed as
the latest version rather than 0.43.4. Separately, the current
repository link on the pixman page [2] links to a dead URL, I believe
it should be updated to instead link to [3].

Thanks,
Shaun

1. https://www.cairographics.org/releases/
2. https://pixman.org/
3. https://gitlab.freedesktop.org/pixman/pixman