feat(docker): do not run container as root

Using a non root user to execute the application.
We don't need to be root

misc/docker/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.17 AS build
+FROM reg.cadoles.com/dh/library/golang:1.17 AS build
 
 ARG HTTP_PROXY=
 ARG HTTPS_PROXY=
@@ -23,12 +23,15 @@ RUN npm install \
     && echo "---" > ./misc/release/config-patch.yml \
     && make ARCH_TARGETS=amd64 release
 
+
 FROM busybox
 
-COPY --from=build /src/release/fake-sms-linux-amd64 /app
+RUN adduser -D -h /app sms
 
+COPY --from=build /src/release/fake-sms-linux-amd64 /app
+RUN chown -R sms:sms /app
+
+USER sms
 WORKDIR /app
 
-RUN mkdir -p /app
-
 CMD ["bin/fake-sms", "--config", "config.yml"]