feat: upgrade Timber requirements (PHP 8.1/WP 6.0/Twig 3.5)

[nlemoine]

• PHP >=8.1
• WP >=6.0
• Twig >= 3.5
• Remove symfony/polyfill-php80
• Update workflow matrix accordingly

Issue

As previously discussed, Timber >=2.1 will drop support for PHP <= 8.1 and WP <= 6.0.

Packagist stats shows pretty wide 8.1+ adoption and we should encourage users to move forward.

Solution

Impact

Usage Changes

Considerations

Twig <= 3.5 has security issues, so I bumped directly to Twig 3.5:

Testing

[szepeviktor]

Half of the WordPress ecosystem (core, plugins, themes) runs on PHP 7.4.
https://wordpress.org/about/stats/#php_versions
Dropping it may be too early.

[mikelittle]

Half of the WordPress ecosystem (core, plugins, themes) runs on PHP 7.4. https://wordpress.org/about/stats/#php_versions Dropping it may be too early.

I disagree. Those who insist on sticking with an out of date version of PHP can stick with Timber 1.x

[szepeviktor]

All right. One can upgrade/fix core, the theme, and self-created plugins but how about other plugins?

[rmens]

This is the type of discussion that will keep the ecosystem on PHP 7.4 indefinitely.

[nlemoine]

This is the type of discussion that will keep the ecosystem on PHP 7.4 indefinitely.

💯 Agreed! I may also add:

• Timber 2 is a library and now composer only, this means it will probably target more "advanced" users. WordPress stats ≠ Timber stats. I'm running all my projects on PHP 8.1 without any problems since a year or so. Some of them are even running PHP 8.2 smoothly.
• If the plugin/theme/package you're using crashes your site or fills the screen/logs with notices/warnings in debug mode on PHP 8+, this is a bad quality signal (at least to me) and actually a good hint that you may want to find a better candidate
• Finally, supporting wide version ranges requires a lot of time and work, I often found myself fixing tests that were passing on some version and not another. It makes testing and developing more complicated. Considering Timber stats, I think it's not worth it and we can't afford that extra effort, I'm sure users will understand.