Introduce automated deploy to WP.org

Ported from 10up's GitHub Action: https://github.com/10up/actions-wordpress/blob/598b1572d5024340f09d7efc083a65ebff3bcdef/dotorg-plugin-deploy/entrypoint.sh

.gitlab-ci.yml

@@ -46,6 +46,8 @@ PHPunit:PHP7.3:MySQL:
 
 PluginSVN:
   stage: deploy
+  before_script:
+    - date
   script: ./bin/deploy.sh
   when: on_success
 #  only: