Remove USER directive from dockerfile.

Seems to clash with implicit in after out, since the target volume
is owned by root.

Dockerfile

@@ -3,6 +3,5 @@ FROM alpine
 RUN apk --no-cache add bash openssh-client jq gettext \
  && adduser --no-create-home --uid 1000 -D user \
  && mkdir -p /opt/resource/
-USER 1000:1000
 WORKDIR /opt/resource/
 COPY src/ /opt/resource/