Add CI/CD image build

.gitlab-ci.yml

+stages:
+  - publish
+
+variables:
+  CONTAINER_IMAGE: gitlab-registry.eps.surrey.ac.uk/lz0002/hello
+
+build:
+  image: docker:latest
+  stage: publish
+  services:
+    - docker:dind
+  script:
+    - docker login -u cicd -p x8x_9DwsywDzAPviBX7s
+    - docker build -t ${CONTAINER_IMAGE} .
+    #- docker tag ${CONTAINER_IMAGE} ${CONTAINER_IMAGE}:${CI_COMMIT_SHORT_SHA}
+    - docker tag ${CONTAINER_IMAGE} ${CONTAINER_IMAGE}:latest
+    - docker push ${CONTAINER_IMAGE}:latest
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