Upgrading the edx-organizations package to 0.4.7.

Added explicit 'fields' attribute to OrganizationSerializer. Creating a
ModelSerializer without either the 'fields' attribute or the 'exclude'
attribute has been deprecated since 3.3.0.

LEARNER-2320

requirements/edx/base.txt

@@ -50,7 +50,7 @@ edx-django-sites-extensions==2.3.0
 edx-enterprise==0.51.1
 edx-oauth2-provider==1.2.2
 edx-opaque-keys==0.4.0
-edx-organizations==0.4.6
+edx-organizations==0.4.7
 edx-rest-api-client==1.7.1
 edx-search==1.1.0
 edx-submissions==2.0.12