chore(docker): run as non root user in container (#727)

docker/Dockerfile

@@ -2,17 +2,24 @@ FROM alpine:3.17
 
 ARG TARGETOS
 ARG TARGETARCH
+ARG USER=gorush
+ENV HOME /home/$USER
 
 LABEL maintainer="Bo-Yi Wu <appleboy.tw@gmail.com>" \
   org.label-schema.name="Gorush" \
   org.label-schema.vendor="Bo-Yi Wu" \
   org.label-schema.schema-version="1.0"
 
+# add new user
+RUN adduser -D $USER
 RUN apk add --no-cache ca-certificates mailcap && \
   rm -rf /var/cache/apk/*
 
 COPY release/${TARGETOS}/${TARGETARCH}/gorush /bin/
 
+USER $USER
+WORKDIR $HOME
+
 EXPOSE 8088 9000
 HEALTHCHECK --start-period=1s --interval=10s --timeout=5s \
   CMD ["/bin/gorush", "--ping"]