Refactor OpenAI config and prompt functions.

- Use OpenAI config in `Client` initialization
- Refactor `with_api_key()` method to `OpenAIConfig::with_api_key()`
- Add generic type parameter to `chat_completion` and `completion` functions in `prompt.rs`

src/cli.rs

@@ -1,5 +1,6 @@
 use crate::prompt;
 use anyhow::bail;
+use async_openai::config::OpenAIConfig;
 use async_openai::Client;
 use clap::{command, value_parser, Parser};
 use std::fs::File;
@@ -69,7 +70,8 @@ pub(crate) async fn main() -> anyhow::Result<()> {
         bail!("OPENAI_API_KEY must be set");
     };
 
-    let client = Client::new().with_backoff(backoff).with_api_key(api_key);
+    let client = Client::<OpenAIConfig>::with_config(OpenAIConfig::new().with_api_key(api_key))
+        .with_backoff(backoff);
 
     let input = get_prompt_from_input(&cli.files)?;
 

src/prompt.rs

@@ -1,5 +1,6 @@
 use anyhow::bail;
 use async_openai::{
+    config::Config,
     types::{
         ChatCompletionRequestMessageArgs, CreateChatCompletionRequestArgs,
         CreateCompletionRequestArgs, Role,
@@ -16,8 +17,8 @@ pub(crate) fn should_use_chat_completion(model: &str) -> bool {
     model.to_lowercase().starts_with("gpt-4") || model.to_lowercase().starts_with("gpt-3.5-turbo")
 }
 
-pub(crate) async fn chat_completion(
-    client: &Client,
+pub(crate) async fn chat_completion<C: Config>(
+    client: &Client<C>,
     prompt: &str,
     model: &str,
     cli: &CompletionArgs,
@@ -74,8 +75,8 @@ pub(crate) async fn chat_completion(
 
     Ok(())
 }
-pub(crate) async fn completion(
-    client: &Client,
+pub(crate) async fn completion<C: Config>(
+    client: &Client<C>,
     prompt: &str,
     model: &str,
     cli: &CompletionArgs,