prettierx: update yarn.lock --dev (#519)

* remove jest-watch-typeahead from devDependencies
* remove snapshot-diff from devDependencies
* remove jest from devDependencies
* remove babel-loader from devDependencies
* remove terser-webpack-plugin from devDependencies
* remove webpack from devDependencies
* add jest (version 26.6.3) to devDependencies
* add jest-watch-typeahead (version 0.6.2) to devDependencies
* add snapshot-diff (version 0.8.1) to devDependencies
* add webpack@4.46.0 to devDependencies
* add babel-loader (version 8.2.2) to devDependencies
* add terser-webpack-plugin@4.2.3 to devDependencies