Patch HTTPProxy mixins to use extra_headers - related to issue #556

[matthieupinte]

Changes

Please describe both what is changing and why this is important. Include:

Change Auth0::Mixins::HTTPProxy#request method to take extra_headers into account, for all request type.

References

Related to MFA API Bearer token issue #556

The gem does not take extra_headers into account in that case https://github.com/auth0/ruby-auth0/blob/master/lib/auth0/mixins/httpproxy.rb#L95

Please note any links that are not publicly accessible.

Testing

Please describe how this can be tested by reviewers. Be specific about anything not tested and reasons why. If this library has unit and/or integration testing, tests should be added for new functionality and existing tests should complete without errors.

• This change adds unit test coverage
• This change adds integration test coverage
• This change has been tested on the latest version of Ruby

Checklist

• I have read the Auth0 general contribution guidelines
• I have read the Auth0 Code of Conduct
• All existing and new tests complete without errors
• Rubocop passes on all added/modified files
• All active GitHub checks have passed