[VOL-3957] Including latest openolt version (3.1.8) in VOLTHA-2.7

Change-Id: I6578a7707118dbd2604dfec3224e07fd7279e9ed
diff --git a/voltha-adapter-openolt/Chart.yaml b/voltha-adapter-openolt/Chart.yaml
index e349e97..002985d 100644
--- a/voltha-adapter-openolt/Chart.yaml
+++ b/voltha-adapter-openolt/Chart.yaml
@@ -14,7 +14,7 @@
 ---
 apiVersion: "v1"
 name: "voltha-adapter-openolt"
-version: "2.8.7"
+version: "2.8.8"
 description: "A Helm chart for Voltha OpenOLT Adapter"
 keywords:
   - "onf"
@@ -33,4 +33,4 @@
 
 # appVersion refers to multiple components with potentially different
 # container image versions.
-appVersion: "3.1.7"
+appVersion: "3.1.8"