Bumping VOLTHA charts version to leave space for bugfixes in voltha-2.6

Change-Id: Ibbee5d0bd39e4b2e0364d5f2a8c16196ff6d924a
diff --git a/voltha-adapter-openolt/Chart.yaml b/voltha-adapter-openolt/Chart.yaml
index 141f832..a3d8ec5 100644
--- a/voltha-adapter-openolt/Chart.yaml
+++ b/voltha-adapter-openolt/Chart.yaml
@@ -14,7 +14,7 @@
 ---
 apiVersion: "v1"
 name: "voltha-adapter-openolt"
-version: "2.7.1"
+version: "2.8.0"
 description: "A Helm chart for Voltha OpenOLT Adapter"
 keywords:
   - "onf"