Update sites.yml

[CellDynamics]

Edited QuimP update site

[ctrueden]

@CellDynamics Thanks for keeping the URL up to date! Note that existing Fiji installations with the QuimP update site enabled might not magically switch over to the new URL; that's what the id: field is supposed to help enable, but I can't remember if we ever ended up implementing it. So you should probably test what happens now that this PR is merged. If it doesn't work, let me know, and we can look into making transitions like this smoother with a future version of the ImageJ Updater.