Update .gitlab-ci.yml file

.gitlab-ci.yml

-deploy:
-    script: "deploy"
-    environment:
-        name: review/$CI_COMMIT_REF_NAME
-        deployment_tier: development
-        url: https://gitlab.com
-    rules:
-        - if: $CI_ENVIRONMENT_NAME =~ /^review\// && $CI_ENVIRONMENT_ACTION == "start" && $CI_ENVIRONMENT_TIER == "development" && $CI_ENVIRONMENT_URL == "https://gitlab.com"
+stages:
+  - stage-1
+  - stage-2
+  - stage-3
+
+deploy-a:
+  stage: stage-1
+  script: echo
+  environment: prd
+  when: manual
+
+deploy-b:
+  stage: stage-2
+  script: echo
+  environment: prd
+  when: manual
+
+deploy-c:
+  stage: stage-3
+  script: echo
+  environment: prd
+  when: manual