style: use type hints for input arguments

[inspiralpatterns]

https://github.com/stoyan-stoyanov/llmflows/blob/6ce79a8cc3b06e799d2b6eb6f6e8e78354f68dcd/llmflows/llms/openai.py#L55

It would be much appreciated if you used type hints for the input arguments in your methods - with this suggestion extended to the whole code base.

[stoyan-stoyanov]

makes sense