Mark typescript dependency as optional

[ai]

Both yarn and npm support peerDependenciesMeta.

Right now if you are using eslint-plugin-prettierx for a non-TS project you will have a warning:

warning " > eslint-plugin-prettierx@0.12.1" has unmet peer dependency "typescript@>=3.2.0".

peerDependenciesMeta will suppress this warning.

[aMarCruz]

@ai , thanks! I didn't know that keyword.