fix: require jest diff properly for version 27

jest with version 27 exports only a named export for the diff
function, so we had to fix the master branch here.

https://github.com/facebook/jest/blob/d38156ccd7a68e52372b4eb6fc02afbadd5b703e/packages/jest-diff/src/index.ts#L63
Co-authored-by: Björn Brauer <bjoern.brauer@new-work.se>

src/run.js

@@ -1,7 +1,7 @@
 const { highlight } = require("cli-highlight");
 const { pass, fail } = require("create-jest-runner");
 const fs = require("fs");
-const diff = require("jest-diff");
+const { diff } = require("jest-diff");
 const prettier = require("prettier");
 
 module.exports = ({ testPath }) => {