test: fix multi-sudo dockerfile

Signed-off-by: CrazyMax <[email protected]>

Author: crazy-max

test/multi-sudo.Dockerfile

@@ -1,5 +1,8 @@
 # syntax=docker/dockerfile:1
-FROM --platform=$BUILDPLATFORM golang:alpine AS build
+
+ARG ALPINE_VERSION=3.21
+
+FROM --platform=$BUILDPLATFORM alpine:${ALPINE_VERSION} AS build
 ARG TARGETPLATFORM
 ARG BUILDPLATFORM
 RUN echo "I am running on $BUILDPLATFORM, building for $TARGETPLATFORM" > /log
@@ -12,9 +15,9 @@ RUN apk --update --no-cache add \
   && rm -rf /tmp/* /var/cache/apk/*
 
 USER buildx
-RUN sudo chown buildx. /log
+RUN sudo chown buildx: /log
 USER root
 
-FROM alpine
+FROM alpine:${ALPINE_VERSION}
 COPY --from=build /log /log
 RUN ls -al /log