Fix npm install in example_check

examples/example_check.py

@@ -76,7 +76,7 @@ async def run_browser(url):
         if not osp.exists(target):
             os.makedirs(osp.join(target))
         await run_async_process(["npm", "init", "-y"], cwd=target)
-        await run_async_process(["npm", "install", "puppeteer^4"], cwd=target)
+        await run_async_process(["npm", "install", "puppeteer@^4"], cwd=target)
     shutil.copy(osp.join(here, 'chrome-example-test.js'), osp.join(target, 'chrome-example-test.js'))
     await run_async_process(["node", "chrome-example-test.js", url], cwd=target)