This switches us over to using a [fork](https://github.com/CommE2E/olm/releases/tag/v0.0.1) of Olm [latest](https://gitlab.matrix.org/matrix-org/olm/-/tree/0eb4550a8f1f393a57c26b93f574097347c152f7).
The fork is mostly Anunay's work to add X3DH support, plus @jon's work to add Nix build support for macOS, plus some fixes from me.
To review this you'll probably want to check the [fork's commit history on GitHub](https://github.com/CommE2E/olm/commits/v0.0.1). We should probably set up some way to review the stuff in the fork, but I'm not sure what the best approach is yet. For now, I've left comments directly on @anunay's [commit on GitHub](https://github.com/CommE2E/olm/commit/31c935d5ed75c1cbf51d9f84ecaccc5d0719803b).