release (#4414)

* Remove draft draft from notes, and prepare to release
Signed-off-by: Miek Gieben <miek@miek.nl>

* fix time
Signed-off-by: Miek Gieben <miek@miek.nl>

* remove draft=true
Signed-off-by: Miek Gieben <miek@miek.nl>

* Remove manifest-tool installation

This doesn't install cleanly anymore. I've installed manifest-tool in
/usr/bin on the releaser machine; use that instead of building our own
each time.
Signed-off-by: Miek Gieben <miek@miek.nl>

* Check for manifest-tool to be available; otherwise we tag a release and then fail
Signed-off-by: Miek Gieben <miek@miek.nl>

Makefile.release

@@ -47,6 +47,9 @@ COMMA:=$(EMPTY),$(EMPTY)
 ifeq (, $(shell which curl))
     $(error "No curl in $$PATH, please install")
 endif
+ifeq (, $(shell which manifest-tool))
+    $(error "No manifest-tool in $$PATH, please install")
+endif
 
 DOCKER:=
 NAME:=coredns
@@ -60,14 +63,10 @@ PLATFORMS:=$(subst $(SPACE),$(COMMA),$(foreach arch,$(LINUX_ARCH),linux/$(arch))
 all:
 	@echo Use the 'release' target to build a release, 'docker' for docker build.
 
-release: pre build tar
+release: build tar
 
 docker: docker-build
 
-.PHONY: pre
-pre:
-	GO111MODULE=off go get github.com/estesp/manifest-tool
-
 .PHONY: build
 build:
 	@echo Cleaning old builds