This was quite simple, I had just to create a simple Gitlab pipeline job and publish to pages this is done by:

image: clojure:lein-2.7.0

before_script:
  - lein deps

test:
  script:
    - lein test

pages:
  stage: deploy
  script:
    - lein package
  artifacts:
    paths:
      - public
  only:
    - master

before_script

will download all the dependencies with lein deps.

test

it is self explanatory

pages

it will compile cljs into js with lein package into public folder to later be published into gitlab pages. Take a look at the artifacts property, it is used to say wich will will be collected.