Pepare Dockerfile for Renovate

Dockerfile

@@ -1,11 +1,8 @@
 # https://aws.amazon.com/blogs/aws/new-for-aws-lambda-container-image-support/
-ARG RUNTIME_VERSION="3.9"
-
 # libexec is missing from >=3.17
-ARG DISTRO_VERSION="3.16"
 
 # Stage 1 - bundle base image + runtime
-FROM python:${RUNTIME_VERSION}-alpine${DISTRO_VERSION} AS python-alpine
+FROM python:3.9-alpine3.16 AS python-alpine
 
 # Install GCC (Alpine uses musl but we compile and link dependencies with GCC)
 RUN apk upgrade -U --available --no-cache && \