Fix Werkzeug DeprecationWarning

[compyman]

Description of the change

This PR changes the flask integration setup to import Request instead of BaseRequest from Werkzeug.

This is motivated by the deprecation warning I'm receiving that says:

{pyenv_dir}/site-packages/rollbar/__init__.py:1160: DeprecationWarning: 'BaseRequest' is deprecated and will be removed in Werkzeug 2.1. Use 'isinstance(obj, Request)' instead.
if WerkzeugRequest and isinstance(request, WerkzeugRequest):

All the tests pass, and I can't on the face of it see a reason to prefer BaseRequest over Request generally

Type of change

• [ ] Bug fix (non-breaking change that fixes an issue)
• [ ] New feature (non-breaking change that adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] Maintenance
• [ ] New release

Checklists

Development

• [ ] Lint rules pass locally My flake8 does not pass locally, but none of those are related to this change
• [x] The code changed/added as part of this pull request has been covered with tests
• [x] All tests related to the changed code pass in development

Code review

• [x] This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• [ ] "Ready for review" label attached to the PR and reviewers assigned
• [ ] Issue from task tracker has a link to this pull request
• [ ] Changes have been reviewed by at least one other engineer