How to get previously released extension versions on Packagist

[asgrim]

Originally ThePHPF/pie-design#17

Since already released versions of an ext don't have a composer.json , they don't list on Packagist, naturally:

* https://packagist.org/packages/xdebug/xdebug

One approach may be for Packagist to process package.xml content for old versions where composer.json does not exist. Need to have a think and see if it is plausible, or if there are other better approaches.

[asgrim]

Note: since php/pie#24 was merged, it is now possible to install specific commits, therefore if you want to install a pre-PIE version, you could refer to the commit for the tag.

e.g. if you wanted to install Xdebug 3.3.0 instead of the latest, you could use:

$ bin/pie install xdebug/xdebug:dev-master#15d672e84caa6015d1b2b509aa13a0528d6e9a7e

Not as clean, but it's something at least.