Fix dumb-init entrypoint (#251)

diff --git a/Dockerfile b/Dockerfile
index a4bce83..a70fe36 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -186,5 +186,5 @@
 
 EXPOSE 80 8080 8423 9000
 
-ENTRYPOINT ["/usr/local/bin/dumb-init", "--"]
+ENTRYPOINT ["/usr/bin/dumb-init", "--"]
 CMD ["/etc/init-container.sh"]