fix version for marshmallow-jsonapi

[Manish Devgan]

Hi,

I was setting up the project again and could not get the deployment working on my local machine.
The issue is that the new Marshmallow-JsonAPI does not return back a Tuple when loading the data into a schema. Initially, it used to return a tuple (data, error) which is not the case now. And in case of a fresh install, the requirements.txt file does not justify which version of Marshmallow-JsonApi needs to be installed. Hence this creates a bundle of errors due to inappropriate unpacking of data.
Please check the requirements.txt file in the backend folder for the same.

I am providing a fix for the same in a PR the link to which I will attach in a moment.

Cheers!
Manish Devgan

[Manish Devgan]

Pull Request #2186