Drop Release label in favor of OSBS release_bump plugin.

OSBS can automatically bump the release number, for that
we just need to drop the label from the Dockerfile

See https://pagure.io/ContainerSIG/container-sig/issue/1

Signed-off-by: Clement Verna <cverna@tutanota.com>

Dockerfile

@@ -1,11 +1,10 @@
 FROM registry.fedoraproject.org/fedora:28
 MAINTAINER "Fedora Infrastructure" <admin@fedoraproject.org>
 
-ENV VERSION=0.7.3 RELEASE=1 SUFFIX=fc28
+ENV VERSION=0.7.3
 LABEL BZComponent="mirrormanager2-mirrorlist" \
 	Name="$FGC/mirrormanager2-mirrorlist" \
 	Version="$VERSION" \
-	Release="$RELEASE" \
 	Architecture="x86_64"
 
 RUN dnf install -y mirrormanager2-mirrorlist httpd mod_wsgi