Updates a contact's details. Send only the fields you want to change inside a contact object.
The writable fields are first_name, last_name, company_name, email, phone,
secondary_phone, address_line1, address_line2, city, state, zip_code, country,
contact_type, notes, email_opt_in, sms_opt_in, call_opt_in and assigned_sales_rep_id.

A contact must keep a phone number, and email must be a valid address if present. An
assigned_sales_rep_id that isn't a user you can assign is cleared rather than rejected. To manage
the contact's properties, use the Addresses endpoints.

The token's user must be able to see the contact.