Add test data for conversation evals

[sourabhagr]

Conversation evals expects a conversation schema:

[
{"role": "user", "content": "hi, can you tell me what is the capital of France?"},
{"role": "assistant", "content": "sure"},
....
]

Data needs to be defined at: "uptrain/tests/test_builtins.py"

[Dominastorm]

Solved by #565