Use latest tag on Dockerfile image references (#75) (#76)

Cherry picked from commit 8cfdb44

build/Dockerfile

@@ -1,5 +1,5 @@
 # --- build smart gateway ---
-FROM registry.access.redhat.com/ubi8 AS builder
+FROM registry.access.redhat.com/ubi8:latest AS builder
 ENV GOPATH=/go
 ENV D=/go/src/github.com/infrawatch/sg-core
 
@@ -13,7 +13,7 @@ RUN dnf install golang git qpid-proton-c-devel -y --setopt=tsflags=nodocs
 RUN PRODUCTION_BUILD=true ./build.sh
 
 # --- end build, create smart gateway layer ---
-FROM registry.access.redhat.com/ubi8-minimal
+FROM registry.access.redhat.com/ubi8-minimal:latest
 
 LABEL io.k8s.display-name="Smart Gateway" \
       io.k8s.description="A component of the Service Telemetry Framework on the server side that ingests data from AMQP 1.x and provides a metrics scrape endpoint for Prometheus, and forwards events to ElasticSearch" \