Seen in the wild at https://github.com/thomaslevesque/FakeItEasy/blob/19f6cbcd444c443949eb3a9f43ce52d4eebb65e4/src/FakeItEasy/FakeItEasy.csproj#L18 when using Refined GitHub 1.19.0, it looks like

<PackageProjectUrl>https://fakeiteasy.github.io/<;/PackageProjectUrl>

Here's an image, just in case:

Note that the semicolon is not really there, as can be seen in the raw view.