Add nginx alpine to update-dependencies task

Makefile

@@ -4,6 +4,7 @@
 update-dependencies:
 	docker pull jwilder/docker-gen:0.7.3
 	docker pull nginx:1.11.3
+	docker pull nginx:1.11.3-alpine
 	docker pull python:3
 	docker pull rancher/socat-docker:latest
 	docker pull appropriate/curl:latest