Bumping olt-service to 2.1.5

Change-Id: I0bb046ce07376d7a0cb2ad1d62312d5ed51712d2
diff --git a/xos-services/volt/Chart.yaml b/xos-services/volt/Chart.yaml
index 1c2b862..1f9724f 100644
--- a/xos-services/volt/Chart.yaml
+++ b/xos-services/volt/Chart.yaml
@@ -18,4 +18,4 @@
 icon: https://guide.opencord.org/logos/cord.svg
 
 version: 2.1.3
-appVersion: 2.1.4
+appVersion: 2.1.5