feat: update gitlab-ci and dockerfile

.gitlab-ci.yml

@@ -1,9 +1,10 @@
 stages:
-  - build
+  - build-app
+  - build-image
   - deploy
 
-build-app:
-  stage: build
+build-1:
+  stage: build-app
   image: golang:alpine
   script:
     - go build -o main .
@@ -11,8 +12,8 @@ build-app:
     paths:
       - main
 
-build-image:
-  stage: build
+build-2:
+  stage: build-image
   image: docker:stable
   services:
     - docker:dind