Sigh, okay, made a mistake, releasing 1.5.8-1.

(I ran `make release` without a GITHUB_TOKEN, which tagged and pushed, but subsequently of course
the tag already exists which is a failure.  Having fixed _that_, goreleaser rightly moaned about the
tag not pointing at HEAD which we were attempting to release. Sigh)

Makefile

@@ -1,4 +1,4 @@
-VERSION ?= 1.5.8
+VERSION ?= 1.5.8-1
 GIT_HASH = $(shell git rev-parse --short HEAD)
 DELIVERY_ENGINEERING_GPG_KEY = 4306B2215879C678