feat: clean up environment call outs

Author: stainless-app[bot]

README.md

@@ -83,15 +83,14 @@ pip install brand.dev[aiohttp]
 Then you can enable it by instantiating the client with `http_client=DefaultAioHttpClient()`:
 
 ```python
-import os
 import asyncio
 from brand.dev import DefaultAioHttpClient
 from brand.dev import AsyncBrandDev
 
 
 async def main() -> None:
     async with AsyncBrandDev(
-        api_key=os.environ.get("BRAND_DEV_API_KEY"),  # This is the default and can be omitted
+        api_key="My API Key",
         http_client=DefaultAioHttpClient(),
     ) as client:
         brand = await client.brand.retrieve(