whitelistPatterns defined in package.json does not work

[franciscolourenco]

Describe the bug
whitelistPatterns/whitelistPatternsChildren defined inside of package.json files don't work, probably because they are strings, not regexes. The following error is thrown while building:

TypeError: v.test is not a function

To Reproduce

1. Config the whitelistPatternsChildren option in package.json via postcss-load-config.
2. Build.

Expected behavior
Strings found inside whitelistPatterns/whitelistPatternsChildren should be converted into regexes.

Screenshots
package.json

  "postcss": {
    "plugins": {
      "tailwindcss": "./tailwind.config.js",
      "vue-cli-plugin-tailwind/purgecss": {
        "whitelistPatternsChildren": ["/^el-/"],
      },
      "autoprefixer": {}
    }
  },

Desktop (please complete the following information):

• OS: macOS
• Version of Purgecss "@fullhuman/postcss-purgecss": "^1.1.0"