[0.4] Bump minimum PHP to 7.4

[mbabker]

Unblocks #51

Based on https://packagist.org/packages/ratchet/rfc6455/php-stats#0.3 it would cover 75% of active consumers of this library (with PHP 7.2 and 7.3 being another 20% combined).

[cboden]

Given https://www.php.net/supported-versions.php I was even considering requiring 7.4. With v0.3.* keeping really old BC compatibility with a few updates soon, I'd be ok with making a bigger jump for v0.4.

Thoughts?

[mbabker]

That works too. Originally I was going to jump straight to 7.4, but there's still a sizeable chunk of users on 7.2 and 7.3 so I broadened it just a bit.

[cboden]

Thanks Michael. I re-targeted against the v0.4 branch. There's a conflict since we corrected some stuff for v0.3.1.

Shall we drop Guzzle 1 support?

[mbabker]

There's a conflict since we corrected some stuff for v0.3.1.

That's fixed.

Shall we drop Guzzle 1 support?

I wouldn't just yet. The 1.8 branch just got a new release a couple of months ago and the 1.x installs are still 2:1 over the 2.x installs, so it sounds like the long tail of consumers of that package might take a little while to catch up on it.

[cboden]

That works too. Originally I was going to jump straight to 7.4, but there's still a sizeable chunk of users on 7.2 and 7.3 so I broadened it just a bit.

v0.3.1 can still be used by users who are using unsupported versions.