2.1

CHANGES:

• Update to mirage-crypto-rng 1.2.0 (@talex5 #313).
  There is no need to do Mirage_crypto_rng_eio.run now.

• Restorer.Table.create now takes a switch (@talex5 #306).
  The table is now cleared when the switch finishes. Avoids having to remember to set this up manually.

• Update README now that 2.0 is released (@talex5 #307 #308).

Build and opam metadata:

• OCaml 5.2 is the minimum version (@talex5 #305).

• Update Windows CI (@smorimoto #310 #311).

• Add x-maintenance-intent to opam files (@talex5 #315, requested by @hannesm).

• Remove capnp-rpc-lwt compatibility package (@talex5 #314).
  The existing release should continue working; no point releasing an unchanged version every time there's a capnp-rpc release.