[webcompat_platform_without_keyword] Run the rule hourly (#2479)

scripts/cron_run_hourly.sh

@@ -72,4 +72,7 @@ python -m bugbot.rules.multifix_regression --production
 # Copy metadata from duplicates
 python -m bugbot.rules.duplicate_copy_metadata --production
 
+# Add `webcompat:platform-bug` keyword to bugs without a platform keyword
+python -m bugbot.rules.webcompat_platform_without_keyword --production
+
 source ./scripts/cron_common_end.sh