Fix release from #1860 (hotfix #1934).

- Cron job to send weekly email report is processed multiple times. Review scheduling process to send to only one worker.
- Implement mechanism to ensure each email is sent only once to each recipient.
- Improve the way the async task is processed by creating a separate task for each organization, instead of processing all organizations in a single task.
posthog/settings.py
"django.contrib.messages.context_processors.messages",
            ],
        },
    },
]
WSGI_APPLICATION = "posthog.wsgi.application"
# Social Auth
SOCIAL_AUTH_POSTGRES_JSONFIELD = True
SOCIAL_AUTH_USER_MODEL = "posthog.User"
AUTHENTICATION_BACKENDS = (
    "social_core.backends.github.GithubOAuth2",
    "social_core.backends.gitlab.GitLabOAuth2",
    "django.contrib.auth.backends.ModelBackend",
)
SOCIAL_AUTH_PIPELINE = (
    "social_core.pipeline.social_auth.social_details",
    "social_core.pipeline.social_auth.social_uid",
    "social_core.pipeline.social_auth.auth_allowed",
    "social_core.pipeline.social_auth.social_user",
    "social_core.pipeline.user.get_username",
    "social_core.pipeline.social_auth.associate_by_email",
    "posthog.urls.social_create_user",
    "social_core.pipeline.social_auth.associate_user",
    "social_core.pipeline.social_auth.load_extra_data",
    "social_core.pipeline.user.user_details",
)
SOCIAL_AUTH_STRATEGY = "social_django.strategy.DjangoStrategy"
SOCIAL_AUTH_STORAGE = "social_django.models.DjangoStorage"
SOCIAL_AUTH_FIELDS_STORED_IN_SESSION = [
    "invite_id",