looks like parser was moved

[nsubordin81]

Hi bdemers! Thanks for making this and making it public. Looks like it isn't active rn but thought I'd let you know I tried using this one for an oauth2 connection over httpie and at some point in the time since these initial commits looks like httpie changed the place that their global parser object gets defined so now it lives in the httpie.cli.definition module.

I thought about making a PR but it would just to be to change the import statement and then that wouldn't be backwards compatible to versions of httpie before this was made so I settled on an issue instead. once that was fixed I got a 400 but that is likely just the content of my request, so that might be all it needs. Thanks again!