Allow Content-Type to contain 'charset=UTF-8' in POST requests

[jean-luc]

Expected behavior

When making a POST requst – for example when authenticating via /token – API should should accept the request even if charset=UTF-8 is present in the Content-Type header.

For example "Content-Type: application/json;charset=UTF-8"

Actual behavior

API throws an Invalid Credentials error if Content-Type include charset=UTF-8. Common frontend libraries like Axios append charset to Content-Type in POST requests by default.