Resource auth attribute is modified by FalconAuthMiddleware

[volinthius]

In FalconAuthMiddleware the auth attribute of the resource is picked and then modified:

    def _get_auth_settings(self, req, resource):
        auth_settings = getattr(resource, 'auth', {})
        auth_settings['exempt_routes'] = self.exempt_routes
        if auth_settings.get('auth_disabled'):
            auth_settings['exempt_routes'].append(req.uri_template)

        for key in ('exempt_methods', 'backend'):
            auth_settings[key] = auth_settings.get(key) or getattr(self, key)

        return auth_settings

This causes a minor issue with JWTAuthBackend backend during testing when resource is only overriding exempt_methods (not backend). For each test we are creating a fresh OIDC provider instance. However since the auth backend (and JWT key with it) is already set in one test to resource later tests still use that old auth backend (with old JWT key) key and fail.