Too many "async with"

🐣 **Is your feature request related to a problem? Please describe.**

I'm always frustrated when I use get or post method.
I must use "async with" to use get or post method.
So there's a lot of "async with" nesting.

💡 **Describe the solution you'd like**

I hope that I can use it just like httpx.
Ex:
```python
async def main():
async with httpx.AsyncClient() as session:
resposne = await session.get("http://httpbin.org") # I was able to release it without having to do it manually
print(resposne.text)
```

❓ **Describe alternatives you've considered**

Add "self.release" after "await self.read()".
Because I don't need connection after this.

📋 **Additional context**