Upgrade prometheus-operator chart

It's good to keep things up to date generally, but there's a specific
thing I want here: this chart upgrade also upgrades prometheus from
2.13.2 to 2.15.2.  Prometheus 2.15 has a feature which considers the
WAL size when calculating how much disk it's using (see
prometheus/prometheus#5886 ).

Author: philandstuff

charts/gsp-cluster/charts/gsp-monitoring/charts/prometheus-operator-8.5.1.tgz

@@ -1,6 +1,6 @@
 dependencies:
 - name: prometheus-operator
   repository: https://kubernetes-charts.storage.googleapis.com/
-  version: 8.5.1
-digest: sha256:41bf87d8163ce8a01c4c2bbb3eda2f7912f6d4087db23d4f78f50deebdd51b30
-generated: "2020-01-14T17:48:40.106202Z"
+  version: 8.9.2
+digest: sha256:439a9d0297e5ee948604c1a5d7fedce333b3f119d011ac51c3df0af401e09c5d
+generated: "2020-02-25T10:25:19.011139Z"

charts/gsp-cluster/charts/gsp-monitoring/charts/prometheus-operator-8.9.2.tgz

@@ -1,4 +1,4 @@
 dependencies:
   - name: "prometheus-operator"
-    version: 8.5.1
+    version: 8.9.2
     repository: https://kubernetes-charts.storage.googleapis.com/