Use patched async-openai library to work around a few upstream issues

Related to:

- CreateImageEditRequest forces an application/octet-stream content type
  for images (https://github.com/64bit/async-openai/issues/364)

- CreateImageEditRequest only deals with a single image
  (https://github.com/64bit/async-openai/issues/363)

This is a continuation of 8f86289373
and fixes the Image Editing feature for OpenAI.

Cargo.lock

@@ -228,8 +228,7 @@ dependencies = [
 [[package]]
 name = "async-openai"
 version = "0.28.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "14d76e2f5af19477d6254415acc95ba97c6cc6f3b1e3cb4676b7f0fab8194298"
+source = "git+https://github.com/etkecc/async-openai?branch=async-openai-v0.28.1-patched#856953c2d4485342df625fd0525363362075e8a8"
 dependencies = [
  "async-openai-macros",
  "backoff",
@@ -254,8 +253,7 @@ dependencies = [
 [[package]]
 name = "async-openai-macros"
 version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0289cba6d5143bfe8251d57b4a8cac036adf158525a76533a7082ba65ec76398"
+source = "git+https://github.com/etkecc/async-openai?branch=async-openai-v0.28.1-patched#856953c2d4485342df625fd0525363362075e8a8"
 dependencies = [
  "proc-macro2",
  "quote",