New Order class, Item class and Bib properties

Added

• Python 3.13 to unit tests in GitHub actions
• OclcNumber class
  • replaces helper functions previously in from local_values.py:
    • oclcNo_with_prefix, oclcNo_without_prefix, is_oclc_number, has_oclc_prefix, _add_oclc_prefix and _delete_oclc_prefix

Changed

• changed most Bib methods to properties. This follows the pattern that pymarc uses with managed Record attributes:
  • methods changed to properties:
    • audience
    • branch_call_no
    • branch_call_no_field
    • cataloging_date
    • control_number
    • created_date
    • dewey
    • dewey_shortened
    • form_of_item
    • languages
    • lccn
    • main_entry
    • oclc_nos
    • orders
    • overdrive_number
    • physical_description
    • record_type
    • sierra_bib_format
    • sierra_bib_id
    • sierra_bib_id_normalized
    • subjects_lc
    • suppressed
    • upc_number
  • normalize_oclc_control_number and remove_unsupported_subjects are still methods as they attributes of a Bib object
• the pymarc_record_to_local_bib function is now a classmethod for the Bib class
• Order is now a class rather than a NamedTuple
  • Order objects are instantiated from a Field object with an optional following_field parameter

Removed

• helper functions in local_values.py. the functionality has been retained in the Bib, Order, and OclcNumber class