[1.8.x] Removed UpdateCacheMiddleware._session_accessed()
[1.8.x] Removed UpdateCacheMiddleware._session_accessed()

This method is unused since f567d04b249913db4a37adab8ba521cdc974d423

Backport of 0e6091249295b0e06aff2b1b4411819f94a1c529 from master

pquentin/django,h4r5h1t/django-hauthy,pquentin/django,h4r5h1t/django-hauthy,pquentin/django,h4r5h1t/django-hauthy,h4r5h1t/django-hauthy