Add Content-Type Header for Pinecone API Integration

[arpagon]

Issue Description

Currently, in the Vocode library, when making requests to the Pinecone API, the Content-Type header is not explicitly set. This can lead to issues since Pinecone API expects the content type to be application/json. Not setting this header can cause the API to not function as expected.

Suggested Enhancement

It would be beneficial to add a default header for all requests made to the Pinecone API within the Vocode library. Specifically, the header should include 'Content-Type': 'application/json'. This change will ensure proper handling of the requests by the Pinecone API.