Add patch method for subject

[walljcg]

AS A user of the ecoscope core library
I WANT a method for patching my EarthRanger subjects
SO THAT I can update existing subjects

We need a patch method for subjects (similar to events) that lets us update an existing subject

[atmorling]

I've changed this from Feature to Sub-Task because this is quire small and self-contained.

[atmorling]

Now that I've said that - a quick glance at https://mep-dev.pamdas.org/api/v1.0/docs/interactive/ suggests that no patch endpoint exists on the ER API for subjects, there is a POST method which we should probably test to see if it will allow updating an existing subject. If not we're potentially blocked on this.

[cisaacstern]

@walljcg is this related to some feature on ecoscope platform? Or is this simply a convenience for ecoscope core library users (e.g. in a notebook context)? @atmorling and I have removed this from v3 on the assumption this is not relevant to the platform specifically, please revise if we are mistaken.