Merge branch 'master' into develop

CHANGES.md

changelog.d/6996.bugfix

debian/changelog

docs/sample_config.yaml

synapse/__init__.py

synapse/config/_base.pyi

synapse/config/homeserver.py

synapse/config/sso.py

synapse/handlers/auth.py

synapse/handlers/saml_handler.py

synapse/module_api/__init__.py

synapse/res/templates/sso_redirect_confirm.html

synapse/rest/client/v1/login.py

tests/rest/client/v1/test_login.py