Port the test suite to PHP 8

[duboism]

This PR follows #11 and #12. Here we port the test suite to PHP 8. This requires PHP Unit >= 9.3 which requires to drop support for PHP 5.6.

[duboism]

Travis CI no longer works so I manually tested PHP 7.4 to PHP 8.3.0 and it seems that the test suite can be installed on all those versions and all the test pass.

[duboism]

@Neustradamus, sorry for the late answer. I don't have enough privileges to do that, sorry. You should probably contact the PEAR team. As far as I know, there is no such team on GitHub so the only way I know is to use the mailing list at https://pear.php.net/support/lists.php. If you find another way, please tell me.

[duboism]

By the way, I think that there is a version conflict in the current code: for PHP >= 8.0, one needs PHP Unit >= 9.3 but this requires PHP >= 7.3 (see https://phpunit.de/supported-versions.html). So this PR would in fact mean to drop all support for PHP < 7.3.

I will try to see what's possible but in the meantime, we should not merge this.

[duboism]

I think it's better to merge #16 before merging this (see the discussion there).

[duboism]

For this PR, I did some experiments with PHPUnit Polyfills, a library that provides an homogeneous API for a lot of PHPUnit versions with very few code change. It's recommended on PHPUnit home page so I think it's a robust solution. With this, I think I can make the test work from 5.6 up to 8.3.

[duboism]

For this PR, I did some experiments with PHPUnit Polyfills, a library that provides an homogeneous API for a lot of PHPUnit versions with very few code change. It's recommended on PHPUnit home page so I think it's a robust solution. With this, I think I can make the test work from 5.6 up to 8.3.

I opened PR #17 to implement the changes described above. Therefore I will close this PR.