Change baseimage to python:3.9.2-alpine3.13

Change-Id: Idfb073bc623a36114c8ece5a693f57bf2e7afe97
Related-PROD: PRODX-12726
diff --git a/Dockerfile b/Dockerfile
index 41e4859..c21cdf6 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM python:3.8-slim
+FROM python:3.9.2-alpine3.13
 
 WORKDIR /usr/src/app