Longhorn: Upgrade from 1.6.4. to 1.7.3

Change-Id: I4e713a453a6b9e983685e2db550066fd2694609f
diff --git a/charts/longhorn/Chart.yaml b/charts/longhorn/Chart.yaml
index 04e57cc..04c937b 100644
--- a/charts/longhorn/Chart.yaml
+++ b/charts/longhorn/Chart.yaml
@@ -1,5 +1,5 @@
 apiVersion: v1
-appVersion: v1.6.4
+appVersion: v1.7.3
 description: Longhorn is a distributed block storage system for Kubernetes.
 home: https://github.com/longhorn/longhorn
 icon: https://raw.githubusercontent.com/cncf/artwork/master/projects/longhorn/icon/color/longhorn-icon-color.png
@@ -25,4 +25,4 @@
 - https://github.com/longhorn/longhorn-ui
 - https://github.com/longhorn/longhorn-tests
 - https://github.com/longhorn/backing-image-manager
-version: 1.6.4
+version: 1.7.3