ci: conditionally?

Author: kellyjosephprice

.github/workflows/ci.yml

@@ -35,4 +35,4 @@ jobs:
         run: npm i react@${{ matrix.react }} react-dom@${{ matrix.react }}
 
       - name: Run tests on React ${{ matrix.react }}
-        run: npm test
+        run: REACT_VERSION=${{ matrix.react }} npm test

public/index.js

@@ -1,9 +1,14 @@
 import React from 'react';
 import ReactDOM from 'react-dom';
-import { createRoot } from 'react-dom/client';
 
 import syntaxHighlighter, { cmVariableContext } from '../src/index';
 
+let createRoot;
+if (process.env.REACT_VERSION === '18') {
+  // eslint-disable-next-line global-require
+  ({ createRoot } = require('react-dom/client'));
+}
+
 const exampleCode = `curl --request POST
   --url <<url>>
   --header 'authorization: Bearer 123'