fix: backend/requirements/base.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-DJANGOALLAUTH-8600545

backend/requirements/base.txt

@@ -11,7 +11,7 @@ hiredis==1.0.1  # https://github.com/redis/hiredis-py
 django==3.0.7  # pyup: < 3.1  # https://www.djangoproject.com/
 django-environ==0.4.5  # https://github.com/joke2k/django-environ
 django-model-utils==4.0.0  # https://github.com/jazzband/django-model-utils
-django-allauth==0.42.0  # https://github.com/pennersr/django-allauth
+django-allauth==65.3.0  # https://github.com/pennersr/django-allauth
 django-crispy-forms==1.9.1  # https://github.com/django-crispy-forms/django-crispy-forms
 django-redis==4.12.1  # https://github.com/jazzband/django-redis
 # Django REST Framework