feat: Add endpoints for retrieving completed tasks

[7rebux]

Changes

Added two new endpoints from the official Todoist API Documentation including types and tests:

• getCompletedTasksByCompletionDate
• getCompletedTasksByDueDate

Testing

• All tests pass (npm run test)
• TypeScript compilation successful (npm run ts-compile-check)
• Linting passes (npm run lint-check)
• Code formatting verified (npm run format-check)

[scottlovegrove]

This is awesome, thank you @7rebux for the contribution.

[scottlovegrove]

@7rebux This has been released in 5.1.0 of the package.

[realmikkifriend]

Thank you! This resolves my request #288

Here is the documentation for getCompletedTasksByCompletionDate() and getCompletedTasksByDueDate().