chore: remove useless mock config

Author: shervinchen

__mocks__/styled-jsx/css.js

@@ -118,7 +118,7 @@ const config: Config = {
   // rootDir: undefined,
 
   // A list of paths to directories that Jest should use to search for files in
-  roots: ['<rootDir>/packages', '<rootDir>/__mocks__'],
+  roots: ['<rootDir>/packages'],
 
   // Allows you to use a custom runner instead of Jest's default test runner
   // runner: "jest-runner",