The `flake.nix` file used `heartwood` as its source of truth for a lot
of tooling.
The `heartwood` library was pinned to its `1.0.0` version, causing
issues when attempting run `nix develop`.
Instead, modify the inputs to grab the tooling from their source of truth.
The `heartwood` binaries can now be retrieved via the `radicle-node`
entry in the Nix packages registry.
Use this script to update tests/support/heartwood-version and keep the
flake in sync with it.
Alternatively, run the script as
scripts/update-flake $(cat tests/support/heartwood-version)
to bring the flake back into sync.
This also updates the flake.lock and the updates the state of the npm
dependencies when run from a nix-enabled system.
Includes the twemoji assets and a check output that runs all tests
except e2e.
Updates to test/support/heartwood-version must also be reflected in
flake.nix in inputs.heartwood.url.
Fintan Halpenny