Bump mini-css-extract-plugin from 1.0.0 to 1.2.0
Bump mini-css-extract-plugin from 1.0.0 to 1.2.0

Bumps [mini-css-extract-plugin](https://github.com/webpack-contrib/mini-css-extract-plugin) from 1.0.0 to 1.2.0.
- [Release notes](https://github.com/webpack-contrib/mini-css-extract-plugin/releases)
- [Changelog](https://github.com/webpack-contrib/mini-css-extract-plugin/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/mini-css-extract-plugin/compare/v1.0.0...v1.2.0)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
yyc1217/twzipcode-vue,yyc1217/twzipcode-vue