misc/coverage: Bump cache timeout from 5 minutes to 1 hour

Updating origin type counters in coverage widget every hour seems
more reasonable that doing it every 5 minutes as the underlying
database requests are pretty costly.

swh/web/misc/coverage.py

@@ -230,7 +230,7 @@ deposited_origins: Dict[str, Any] = {
     ],
 }
 
-_cache_timeout = 5 * 60
+_cache_timeout = 60 * 60  # one hour
 
 
 def _get_listers_metrics(