investigate ContentNegotiation Middleware

[arhimede]

Bug Report

Q	A
Version(s)	6.0.0.
Version(s)	5.0.0.

Summary

See attached file from a production API
need to be synced the current file with it

https://github.com/dotkernel/api/blob/6.0/src/App/src/Middleware/ContentNegotiationMiddleware.php

synced with

ContentNegotiationMiddleware.php.txt

[alexmerlin]

Implemented in #413