[Feature Request] expose django-allauth `SOCIALACCOUNT_REQUESTS_TIMEOUT` as a Paperless env var

Description Hi, Paperless-ngx currently exposes several django-allauth/social-account settings through PAPERLESS_* env vars for OIDC provider configuration, sign-up behaviour, etc. It would be useful to also expose django-allauth's SOCIALACCOUNT_REQUESTS_TIMEOUT setting, for example as: PAPERLESS_SOCIALACCOUNT_REQUESTS_TIMEOUT When using OIDC with an external identity provider, Paperless connects to it during login via django-allauth. In one of our test/dev envs, which has slower networking, this deployment this intermittently fails with: requests.exceptions.ReadTimeout: HTTPSConnectionPool(...): Read timed out. (read timeout=5) Setting these environment variables does not make any difference: PAPERLESS_SOCIALACCOUNT_REQUESTS_TIMEOUT=15 SOCIALACCOUNT_REQUESTS_TIMEOUT=15 Env vars are present, but Django does not expose the setting: returns: unset and request still uses the default 5-second timeout. Solution is to add support for: PAPERLESS_SOCIALACCOUNT_R…