fix: user set in dockerfile

my organization is currently auditing whether any docker images we run
are currently using the root user. From dockerhub it looks like this
line expands out to `USER :` since the env var names don't match. (see
https://hub.docker.com/layers/hashicorp/consul-template/0.29/images/sha256-32f8ffb8db51809d93488527d63f97d267e2a10c0cbe96dfa5cbc408266211ab?context=explore)
This would fix this so that your images are run as the user you create
earlier in the dockerfile.

Dockerfile

@@ -33,6 +33,6 @@ COPY ./dist/$TARGETOS/$TARGETARCH/$BIN_NAME /bin/
 COPY ./.release/docker-entrypoint.sh /bin/
 ENTRYPOINT ["/bin/docker-entrypoint.sh"]
 
-USER ${NAME}:${NAME}
+USER ${BIN_NAME}:${BIN_NAME}
 CMD /bin/$BIN_NAME