Allow PHP 7.4 when using 2.x

Attaching patch. I'm not 110% certain this is correct but giving it a shot.

Fair enough. I can roll it into a point release this week.

I set it that way because I was not testing against against PHP 7.x and didn't want to break anybody's site, but now that my 2.x branch is stable future updates will be almost entirely JS only, so I might as well relax the requirement.

rolled into 2.0.7.

Automatically closed - issue fixed for 2 weeks with no activity.