feat: RC with correct version number

**Describe the bug**
If I am to release a major update, I expect the release candidate to be something like

1.0.0-hash

but now the rc seems to just use the [manifest](https://github.com/ipfs/aegir/blob/fe833e3d6878594b0c972c1ca4de1b1b6e267c58/src/release-rc.js#L54C50-L54C58) version.

so I get something like

0.x.y-hash

Is the feasible to fix? I guess this would need to integrate with some semantic release library to predict the next version