Is your feature request related to a problem? Please describe.

Support installation of PHP extension via pie command

Describe the solution you'd like

PIE is the new PHP extension installer - a replacement for the old pecl command. See https://github.com/php/pie. It'd be great if the gprc extension could be installed with it.

Additional context

See https://github.com/php/pie/blob/main/docs/extension-maintainers.md for the steps to make this happen. Basically it's:

1. Create a composer.json file in the root of this repository.
2. Register it on packagist.org

I'm happy to do a PR, but I see there is already a composer.json file in the root of this repository. Is this still used for anything?