Remove jsperf.com links from README.md.

[simi]

• service is not available anymore

If the code hosted at those links is available anywhere, I can try to help to port it to other service (like http://jsben.ch/, https://perf.link/, https://jsbench.me/, ...).

[pokoli]

Thanks for your contribution.

I do not think we have the code available somewhere else.

[gabe565]

It looks like jsPerf has moved from jsperf.com to jsperf.app. I'm not sure if they still work as intended, but here are the new benchmark links:

• https://jsperf.app/javascript-csv-parsers/4
• https://jsperf.app/javascript-csv-parsers/3