* use reqwest

* support multipart form
* fix audio apits

examples/audio_transcriptions.rs

@@ -0,0 +1,20 @@
+use openai_api_rs::v1::api::OpenAIClient;
+use openai_api_rs::v1::audio::{AudioTranscriptionRequest, WHISPER_1};
+use std::env;
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let client = OpenAIClient::new(env::var("OPENAI_API_KEY").unwrap().to_string());
+
+    let req = AudioTranscriptionRequest::new(
+        "examples/data/problem.mp3".to_string(),
+        WHISPER_1.to_string(),
+    );
+
+    let result = client.audio_transcription(req).await?;
+    println!("{:?}", result);
+
+    Ok(())
+}
+
+// OPENAI_API_KEY=xxxx cargo run --package openai-api-rs --example audio_translations