Increase operations-per-run (open-telemetry#1527)

We keep getting rate limited, so it's not getting through everything.

Author: tylerbenson

.github/workflows/close-stale.yaml

@@ -22,3 +22,5 @@ jobs:
 
           days-before-stale: 365
           days-before-close: 30
+
+          operations-per-run: 500