feat: add gpt-4 demo

demos/demo-gpt-4.ts

@@ -0,0 +1,35 @@
+import dotenv from 'dotenv-safe'
+import { oraPromise } from 'ora'
+
+import { ChatGPTAPI } from '../src'
+
+dotenv.config()
+
+/**
+ * Demo CLI for testing the GPT-4 model.
+ *
+ * ```
+ * npx tsx demos/demo-gpt-4.ts
+ * ```
+ */
+async function main() {
+  const api = new ChatGPTAPI({
+    apiKey: process.env.OPENAI_API_KEY,
+    debug: true,
+    completionParams: {
+      model: 'gpt-4'
+    }
+  })
+
+  const prompt = 'When should you use Python vs TypeScript?'
+
+  const res = await oraPromise(api.sendMessage(prompt), {
+    text: prompt
+  })
+  console.log(res.text)
+}
+
+main().catch((err) => {
+  console.error(err)
+  process.exit(1)
+})