## Description

Updates the `n0-watcher` dependency to the new version (that has a lot
fewer `Result`s everywhere).
- [x] Depends on n0-computer/net-tools#31
- [x] Needs a release of `net-tools`

## Breaking Changes

- Updated `n0-watcher` from version `0.2` to `0.3`.
  Migration guide for users:
- `endpoint.node_addr().initialized().await?` ->
`endpoint.node_addr().initialized().await` (no `?` needed anymore) and
similarly for `endpoint.home_relay()` and other uses of `Watcher`s.
- `endpoint.node_addr().get()?` -> `endpoint.node_addr().get()` and
similarly for `endpoint.home_relay()` and other uses of `Watcher`s.
- If all you have is a `&impl Watcher` but you need the current value,
then you can't call `Watcher::get` anymore, as that now takes a `&mut
self` instead of `&self`. You can work around this by `.clone()`ing to
an intermediate watcher:
    `watcher_ref.get()` -> `watcher_ref.clone().get()`

## Change checklist
<!-- Remove any that are not relevant. -->
- [x] Self-review.
- [x] Documentation updates following the [style
guide](https://rust-lang.github.io/rfcs/1574-more-api-documentation-conventions.html#appendix-a-full-conventions-text),
if relevant.
- [x] All breaking changes documented.