[magnum] Register PTG interest

Hi all,

If you are interested in attending the Magnum PTG, please fill up your interest in the planning etherpad [1]

The Magnum team is very small and spread across EU and AU/NZ, so it is difficult to find slots that will suit all, but we are going to try :)

P.S. There is already a tentative booking for Wed, 10 Apr, 06-08 UTC, which works for the current Cores. I am still open to shifting if there are overwhelming demand.

[1] https://etherpad.opendev.org/p/apr2024-ptg-magnum-planning