fix start_cursor request type (issue:#498)

[Sho-ki]

Issue on #498

Description

This PR resolves a type mismatch issue encountered when using the start_cursor in database.query.
The current implementation leads to a conflict between string | undefined and string | null in various scenarios involving the cursor.

Changes Made

Updated the type for start_cursor in QueryParameters to accept both null and undefined.

Expected Behavior:

With this change, you will no longer face typing issues when assigning next_cursor from a query response to a variable.

 let databaseId = "<some_id>" let entries = [] let cursor: string | null = null while (true) { const { results, has_more, next_cursor }: QueryDatabaseResponse = await notion.databases.query({ database_id: databaseId, start_cursor: cursor, }) cursor = next_cursor // Now this works without typing issues entries.push(...results) if (!has_more) { break } } return entries

[CLAassistant]

All committers have signed the CLA.

[corradopetrelli]

I also noticed this inconsistency. UP! 😄