Update .gitlab-ci.yml file

.gitlab-ci.yml

+stages:
+  - build_stage
+  - deploy_stage
+
 build:
+  stage: build_stage
   script:
     - apt update -y
     - apt install npm -y
     - npm install
 
 deploy:
+  stage: deploy_stage
   script:
     - apt update -y
     - apt install nodejs -y