ref(crons): Improve typing on MONITOR_CODEC (#69919)

Author: evanpurkhiser

src/sentry/monitors/consumers/monitor_consumer.py

@@ -18,6 +18,7 @@
 from arroyo.types import BrokerValue, Commit, FilteredPayload, Message, Partition
 from django.db import router, transaction
 from sentry_kafka_schemas import get_codec
+from sentry_kafka_schemas.codecs import Codec
 from sentry_kafka_schemas.schema_types.ingest_monitors_v1 import IngestMonitorMessage
 from sentry_sdk.tracing import Span, Transaction
 
@@ -57,7 +58,7 @@
 
 logger = logging.getLogger(__name__)
 
-MONITOR_CODEC = get_codec("ingest-monitors")
+MONITOR_CODEC: Codec[IngestMonitorMessage] = get_codec("ingest-monitors")
 
 CHECKIN_QUOTA_LIMIT = 6
 CHECKIN_QUOTA_WINDOW = 60