Added static sleep after Restart VOLTHA Port Forward keyword in VolthaCompMinorVerRollingUpgrade test to let voltctl establish tcp connection

Change-Id: I1a90e5c46d0c7ef9d12d8d01ea45067dad052433
diff --git a/tests/software-upgrades/Voltha_ComponentsUpgrade.robot b/tests/software-upgrades/Voltha_ComponentsUpgrade.robot
index cb528fa..1058f0b 100755
--- a/tests/software-upgrades/Voltha_ComponentsUpgrade.robot
+++ b/tests/software-upgrades/Voltha_ComponentsUpgrade.robot
@@ -192,6 +192,8 @@
         ...    ${NAMESPACE}    app    ${label}
         Log    ${label}: image, app ver & helm chart after upgrade: ${pod_image_1}, ${app_ver_1} & ${helm_chart_1}
         Restart VOLTHA Port Forward     voltha-api
+        # Static sleep to let voltctl tcp connection establish
+        Sleep    5s
         Verify Provisioned Subscribers
         Unprovision Subscribers
     END