Add PHP 8.1 RC6 to CI

[ruudk]

No description provided.

[ruudk]

@nick-zh Shall we merge this to prepare for PHP 8.1?

[arnaud-lb]

Thanks @ruudk

Could you rebase on 5.x ? I've tried doing it but the build does not pass: https://github.com/arnaud-lb/php-rdkafka/runs/4209963535?check_suite_focus=true

[ruudk]

@arnaud-lb Done, please approve the workflow (you can disable this btw)

[arnaud-lb]

Thanks @ruudk

I've disabled the approval requirement

The build is failing, I think it's because there is no [[ in sh

[ruudk]

@arnaud-lb Seems to be working now 🎉 Only 1 test failure, not sure how to solve that.

[arnaud-lb]

Thanks!

I will fix the test separately

[arnaud-lb]

Unfortunately the error shows that some changes will be necessary around arginfos to support PHP 8.1. I've created an issue, help welcome :) #479