Bump version to 7.12.0

Closes #10 (closed)

Dockerfile

 ARG BASE_REGISTRY=registry1.dsop.io
 ARG BASE_IMAGE=ironbank/redhat/ubi/ubi8
 ARG BASE_TAG=8.3
-ARG LOGSTASH_VERSION=7.11.2
+ARG LOGSTASH_VERSION=7.12.0
 ARG GOLANG_VERSION=1.16
 
 FROM ${BASE_REGISTRY}/${BASE_IMAGE}:${BASE_TAG} AS env2yaml