From the IRC meeting on 2019-12-12 log:

19:08:17 <wumpus> #topic appveyor CI future (sipsorcery)
...
19:25:14 <wumpus> in any case, let'stest it and talk about it next meeting or so
19:25:26 <MarcoFalke> Ok, so unless there are objections: Merge #17736 as short term fix, and then (next week maybe) switch to GitHub Actions CI?
19:25:28 <gribble> #17736 | Update msvc build for Visual Studio 2019 v16.4 by sipsorcery · Pull Request #17736 · bitcoin/bitcoin · GitHub
19:25:41 <sipsorcery> +1
19:25:49 <fanquake> +1
19:25:49 <wumpus> ack
19:25:52 <emilengler> +1

Is it time to set up a CI workflow in this repo?

Pros: see meeting log.
Cons: to be built successfully a PR should be rebased on top of #17793.