test: fix multi-sudo dockerfile

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

test/multi-sudo.Dockerfile

@@ -1,5 +1,6 @@
 # syntax=docker/dockerfile:1
-FROM --platform=$BUILDPLATFORM golang:alpine AS build
+
+FROM --platform=$BUILDPLATFORM alpine AS build
 ARG TARGETPLATFORM
 ARG BUILDPLATFORM
 RUN echo "I am running on $BUILDPLATFORM, building for $TARGETPLATFORM" > /log
@@ -12,7 +13,7 @@ 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