Migrate doesn't work on python 3.6

[marhabaie]

I fixed it manually, but could you please push the latest version so others can get it using "pip install django-podcasting"? Even the final version still has problem. "initial migration with photologue" hasn't been solved yet.

raise ValueError('Related model %r cannot be resolved' % self.remote_field.model) ValueError: Related model 'photologue.Photo' cannot be resolved

these need to get under an "if"? https://github.com/rizumu/django-podcasting/blob/4f4ab9094d6b6b8010ac0b7d6c3158c2413f755a/podcasting/migrations/0005_auto_20190617_1316.py#L19-L23

https://github.com/rizumu/django-podcasting/blob/4f4ab9094d6b6b8010ac0b7d6c3158c2413f755a/podcasting/migrations/0005_auto_20190617_1316.py#L29-L33

Thanks,

[SethAngell]

Proposed a potential fix for this in #31