Automate the API Client generation

[welcoMattic]

As mentioned on Twitter/X to @zenorocha, I think https://github.com/janephp/janephp/ could helps a lot Resend to automatically generate an up to date PHP Client from the OpenAPI specification.

At JoliCode, we already use this to generate a Slack API PHP client. We also use with our clients to generate private API PHP clients based on OpenAPI specification, and update them in a snap.

If such automation is considered, I could open a PR soon with a PoC.

[zenorocha]

At this moment, we're still planning to maintain all SDKs manually, but I appreciate the suggestion.