support batch requests

[shanejonas]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://inspector.open-rpc.org/?url=https://mock.open-rpc.org/petstore-1.0.0
2. paste this into the request editor:

[
    {
        "jsonrpc": "2.0",
        "method": "list_pets",
        "params": [],
        "id": 0
    }
]

3. See error
   

Expected behavior
I should get no errors