Fix cannot create partitions from samples with Patient assigned

[xispa]

Description of the issue/feature this PR addresses

This Pull Request makes it possible to create partitions from samples with a patient assigned

Current behavior before PR

Traceback (innermost last):
  Module ZPublisher.WSGIPublisher, line 176, in transaction_pubevents
  Module ZPublisher.WSGIPublisher, line 385, in publish_module
  Module ZPublisher.WSGIPublisher, line 288, in publish
  Module ZPublisher.mapply, line 85, in mapply
  Module ZPublisher.WSGIPublisher, line 63, in call_object
  Module bika.lims.browser.partition_magic, line 98, in __call__
  Module bika.lims.utils.analysisrequest, line 427, in create_partition
  Module bika.lims.utils.analysisrequest, line 89, in create_analysisrequest
  Module Products.Archetypes.BaseObject, line 685, in processForm
  Module zope.event, line 33, in notify
  Module zope.component.event, line 27, in dispatch
  Module zope.component._api, line 134, in subscribers
  Module zope.interface.registry, line 448, in subscribers
  Module zope.interface.adapter, line 899, in subscribers
  Module zope.component.event, line 36, in objectEventNotify
  Module zope.component._api, line 134, in subscribers
  Module zope.interface.registry, line 448, in subscribers
  Module zope.interface.adapter, line 899, in subscribers
  Module senaite.patient, line 56, in wrapper
  Module senaite.patient.subscribers.analysisrequest, line 32, in on_object_created
  Module senaite.patient.subscribers.analysisrequest, line 94, in update_patient
  Module senaite.patient.api, line 97, in get_patient_by_mrn
AttributeError: 'dict' object has no attribute 'encode'

Desired behavior after PR is merged

Partitions are created and Patient is copied across

--
I confirm I have tested this PR thoroughly and coded it according to PEP8
and Plone's Python styleguide standards.