Flask-pyoidc

* Add token introspection and client credentials flow (120). Huge kudos to infohash for implementing, testing and documenting it.

* Fix `post_logout redirect_uri` when using dynamic client registration (117). Thanks infohash for reporting and fixing it. 👏

- Test fixes (107). Thanks Titotix 👏
- Documentation improvements (103). Thanks Titotix 👏
- Don't remove stored auth request from session prematurely. (112) Thanks to steveqx for reporting it. 👏
- Use default value for 'end_session_state' if it's not stored. (114) Thanks to enkelli for reporting it. 👏
- Fix deprecated collections import for python 3.10. (111) Thanks to ThoreKr. 👏

Important security fixes

* Properly validate the ID token according to the OIDC specification.
Use Client.verify_id_token from pyoidc to verify issuer, audience,
expiry, nonce, acr_values and max_age.
* Upgrade to latest pyoidc version fixing [security issues](https://github.com/OpenIDC/pyoidc/security/advisories/GHSA-4fjv-pmhg-3rfg).

Fixes
* Fix 94: Use correct attribute for error redirect_uri. (96) Thanks to lucasdurand for reporting it. 🙇

Changes
* Allow RedirectUriConfig be specified in OIDCAuthentication constructor. (97) Thanks to em-es-ce for reporting and testing. 🙇

Fixes
* Fix 89: Return error in case unsolicited authentication response. (90) Thanks to enkelli for reporting it. 🙇