Update Dockerfile

Author: AndrewMarchukov

Dockerfile

@@ -3,7 +3,7 @@ FROM alpine:latest
 COPY ./tracker-add-auto.sh /opt/tracker-add-auto.sh
 
 RUN apk add --update \
-        bash transmission-cli curl && \
+        bash transmission-cli curl coreutils && \
         rm -rf /var/cache/apk/* && \
         chmod +x /opt/tracker-add-auto.sh