Djangosaml2

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- Allow a SSO request without any attributes besides the NameID info. Backwards-incompatible changes to allow easier behaviour differentiation, two methods now receive the idp identifier (+ **kwargs were added to introduce possible similar changes in the future with less breaking effect):
- Method signature changed on Saml2Backend.clean_attributes: from `clean_attributes(self, attributes: dict)` to `clean_attributes(self, attributes: dict, idp_entityid: str, **kwargs)`
- Methodignature changed on Saml2Backend.is_authorized: from `is_authorized(self, attributes: dict, attribute_mapping: dict)` to `is_authorized(self, attributes: dict, attribute_mapping: dict, idp_entityid: str, **kwargs)`
- SAML session refactor and minor changes in README file
- local Logout - independent by IdP SLO Response

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- SameSite workaround with a specialized cookie, decoupled from django default

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- Bugfix: Always save newly created users when ATTRIBUTE_MAPPING is missing in the config
- pySAML2 v5.3.0

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- Fixes creating new user with iexact lookup

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- Support several required fields during User creation
- Don't pass sigalg parameter when not signing login request
- ALLOW_SAML_HOSTNAMES validation for redirect
- Custom attribute mapping for Django user model (example)
- Slo absence workaround
- Metadata EntityID exception handling
- Fix unsigned authentication request to POST endpoint
- py38 Test fixes
- CI with Github actions
- Backend restructuring for easier subclassing
- Assertion consumer service now more extensible as a class-based view
with hooks that can be overridden by subclass implementations.

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- Fixed regression from 0.18.0. Thanks to OskarPersson