Merge branch 'django4' into 'master'

.gitlab-ci.yml

Dockerfile

djangoldp/__init__.py

djangoldp/admin.py

djangoldp/apps.py

djangoldp/conf/default_settings.py

djangoldp/conf/ldpsettings.py

...oldp/conf/package_template/app_name/djangoldp_urls.py-tpl

djangoldp/conf/server_template/server/urls.py-tpl

djangoldp/filters.py

djangoldp/middleware.py

djangoldp/models.py

djangoldp/permissions.py

djangoldp/serializers.py

djangoldp/tests/djangoldp_settings.py

djangoldp/tests/djangoldp_urls.py

djangoldp/tests/models.py

djangoldp/tests/tests_get.py

djangoldp/tests/tests_inbox.py

djangoldp/tests/tests_ldp_model.py