ci: add job to automatically publish package to npm

Fixes #18

.gitlab-ci.yml

@@ -17,6 +17,9 @@ build:
   stage: build
   script:
     - npm run build
+  artifacts:
+    paths:
+      - lib
 
 audit:
   stage: test
@@ -33,6 +36,21 @@ scheduled-audit:
   only:
     - schedules
 
+package:
+  dependencies:
+    - build
+  tags:
+    - secrecy
+  stage: deploy
+  script:
+    - echo "//registry.npmjs.org/:_authToken=$NPM_AUTH_TOKEN" > /root/.npmrc
+    - npm publish
+  only:
+    - /^v[0-9]+\.[0-9]+\.[0-9]+$/
+  artifacts:
+    paths:
+      - public
+
 pages:
   stage: deploy
   script: