[bug] Support for LlamaIndex with Pydantic2

[mikeldking]

LlamaIndex recently shipped with pydantic 2 support which seems to be breaking the instrumentaiton:

File ~/Library/Caches/pypoetry/virtualenvs/llama-index-caVs7DDe-py3.11/lib/python3.11/site-packages/openinference/instrumentation/llama_index/_handler.py:157
    153     FINISHED = auto()
    154     IN_PROGRESS = auto()
--> 157 class _Span(
    158     BaseSpan,
    159     extra="allow",
    160     keep_untouched=(singledispatchmethod, property),
    161 ):
    162     _otel_span: Span = PrivateAttr()
    163     _attributes: Dict[str, AttributeValue] = PrivateAttr()
    ```
    
    Yielding an error
    
    ```
    NameError: Private attributes must not use valid field names; use sunder names, e.g. '_end_time' instead of 'end_time'.
    ```
    

[Pyiner]

I encountered the same problem. I hope it can be fixed as soon as possible. Thanks!

[mikeldking]

Thanks @Pyiner - we've marked it as P0 and will get a fix in ASAP!