fix: add regexp to allowed type of options.transpileModules

[magicdawn]

accroding to this https://github.com/egoist/poi/blob/master/core/poi/lib/plugins/config-babel.js#L53-L54
regexp is allowed, AND regexp should be allowd like vue.config.js
but validations fail when regexp is passed

use case

package manager like cnpm use symlink
like prettier module resolve to node_modules/_prettier@1.19.1@prettier

$ ll node_modules/prettier
lrwxr-xr-x  1 magicdawn  staff    25B 12  9 23:19 node_modules/prettier -> _prettier@1.19.1@prettier

regexp can be used to match this /prettier/

[egoist]

Can you update the docs as well? https://poi.js.org/config.html#babel-transpilemodules

[magicdawn]

docs updated: poi-bundler/website#22