Add GitHub Action support for PHP Grpc

[huan]

#76 has added the PHP related scripts for generating the GRPC stubs in PHP, so all the PHP related code will be fully automated after we create its GitHub Action.

It will great if @zhangchunsheng can create another PR to implement it.

[zhangchunsheng]

I will add Github Action when I have time.

[huan]

Awesome! Looking forward to adding the GitHub Action for PHP to our GRPC service!

[zhangchunsheng]

I have added php action.

[huan]

Fantastic! Thank you very much for improving our DevOps pipeline for PHP Wechaty!