ref: fixup mypy blocklist (#50603)

trying to quickfix here but I was too quick:
https://github.com/getsentry/sentry/pull/50601 (fixing the options
exports fixed this module's typing)

pyproject.toml

@@ -988,7 +988,6 @@ module = [
     "sentry.monitors.endpoints.organization_monitor_checkin_attachment",
     "sentry.monitors.endpoints.organization_monitor_details",
     "sentry.monitors.endpoints.organization_monitor_index",
-    "sentry.monitors.endpoints.organization_monitor_stats",
     "sentry.monitors.models",
     "sentry.monitors.utils",
     "sentry.monitors.validators",