Get a new VPS for alpha.social.coop

We decided in a past meeting we'd consider using our discretionary budget to get another VPS, this time to host alpha.social.coop in a way that is maximally representative of our main instance setup. It shouldn't be too expensive given that load is expected to be very low (just testing ground).

We could use hypha if in a pinch, but it's seeded with coop cloud which already hosts SSO and the wiki; some diversification would both make the project easier (as we remove known and potential interferences between coop cloud and ansible) and let us experiment with moving away from Hetzner/having a plan B is the recent worries are something we want to potentially act on.