SEBA-622 add grpcio-reflection

Change-Id: I42fdf76b60d5c69275369b0ab38558c21983a9d3
diff --git a/Dockerfile b/Dockerfile
index 1a9cff0..d16bfaf 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 # xosproject/alpine-grpc-base
-FROM alpine:3.9.2
+FROM alpine:3.9.3
 
 # Install apk packages
 RUN apk add --no-cache \