Update requests-oauthlib to 0.8.0

[pyup-bot]

There's a new version of requests-oauthlib available.
You are currently using 0.7.0. I have updated it to 0.8.0

These links might come in handy: PyPI | Changelog | Repo

Changelog

0.8.0

+++++++++++++++++++++++++

• Added Fitbit compliance fix.
• Fixed an issue where newlines in the response body for the access token
  request would cause errors when trying to extract the token.
• Fixed an issue introduced in v0.7.0 where users passing auth to several
  methods would encounter conflicts with the client_id and
  client_secret-derived auth. The user-supplied auth argument is now
  used in preference to those options.

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖