Update alpine Docker tag to v3.20.3

Author: renovate[bot]

docker/batch-change-volume-workspace/Dockerfile

@@ -2,6 +2,6 @@
 # image that we use to run curl, git, and unzip against a Docker volume when
 # using the volume workspace.
 
-FROM alpine:3.19.1@sha256:c5b1261d6d3e43071626931fc004f70149baeba2c8ec672bd4f27761f8e1ad6b
+FROM alpine:3.20.3@sha256:beefdbd8a1da6d2915566fde36db9db0b524eb737fc57cd1367effd16dc0d06d
 
 RUN apk add --update git unzip