Keep an eye on php-rrule PHP compatibility

[indigoxela]

At some point in (near) future, they might drop php 7.x compatibility, which would force us to also raise requirements.

See: rlanvin/php-rrule#119

[indigoxela]

Looks like there are some preps to require at least 7.3+. Not merged to main branch, yet, but ... the date seem getting closer. 😉

[indigoxela]

... and even closer - the next release (3.x) will drop support for php <7.3:
rlanvin/php-rrule#119 (comment)

[indigoxela]

Strange, their composer.json still states "php": ">=5.6.0", but their readme states PHP >= 7.3. Which one's correct?

Edit: no, their most recent composer.json also states 7.3. So it's time to require that in this module with their next release.