fix: remove jest-validate peer deps

[unional]

The peer deps of jest-validate is actually not needed.

jest-validate will always present in the consuming repo since jest transiently include it as dep:

jest -> jest-cli -> jest-validate

https://github.com/facebook/jest/blob/main/packages/jest/package.json
https://github.com/facebook/jest/blob/main/packages/jest-cli/package.json

This will get rid of the unnecessary peer dep warning.

Fixes #19

[SimenB]

We use jest-validate and shouldn't rely on hoisting. If anything, a regular dependency should be added rather than the peer dep

[unional]

It depends on how you look at it. IMO this is a plugin so if adding jest-validate as a regular dependency you will end up with version compatibility issue, unless it is "jest-validate": "*".

I think the issue is actually at jest side, where in a plugin system it might work better if all code needed by plugins are exported at one place, e.g.:

import { ValidationError } from 'jest' 

Then it is very clear that it should be a peer dependency.