Update alpine Docker tag to v3.20.2

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:3.20.2@sha256:0a4eaa0eecf5f8c050e5bba433f58c052be7587ee8af3e8b3910ef9ab5fbe9f5
 
 RUN apk add --update git unzip