fix(config): parse env variable as int (#359)

- parse SENTRY_EVENT_RETENTION_DAYS as integer in case it is defined as a string like in kubernetes

sentry/sentry.conf.example.py

@@ -29,7 +29,7 @@ SENTRY_USE_BIG_INTS = True
 # and thus various UI optimizations should be enabled.
 SENTRY_SINGLE_ORGANIZATION = True
 
-SENTRY_OPTIONS["system.event-retention-days"] = env('SENTRY_EVENT_RETENTION_DAYS') or 90
+SENTRY_OPTIONS["system.event-retention-days"] = int(env('SENTRY_EVENT_RETENTION_DAYS', '90'))
 
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 # Redis #