fix: import runCLI off default export (fix Nerajno#65)

See the following:

* jestjs/jest#9512 (comment)
* jestjs/jest#8874 (comment)
* stryker-mutator/stryker-js#1983

src/index.js

@@ -1,4 +1,4 @@
-import { runCLI } from '@jest/core';
+const { runCLI } = require('@jest/core');
 import PluginError from 'plugin-error';
 import through2 from 'through2';