fix(tags): rename inherited_tags to _inherited_tag_names in fixtures

CI failure on rest-framework jobs: FieldDoesNotExist on FakeTaggedModel
when loading dojo_testdata_locations.json. The JSON-column rename in
0265 dropped the M2M field, but three fixtures still referenced the old
name. Sweep fixtures alongside the model migration so test setUpClass
loads cleanly.

Author: valentijnscholten