Update .gitlab-ci.yml file

.gitlab-ci.yml

@@ -1,4 +1,4 @@
-image: docker:19.03.12
+#image: docker:19.03.12
 
 # Change pip's cache directory to be inside the project directory since we can
 # only cache local items.
@@ -18,6 +18,7 @@ stages:
 - push
 
 test:
+  image: python:3.8
   stage: test
   before_script:
   - apt-get update && apt-get install python3
@@ -28,11 +29,13 @@ test:
   - pytest
 
 build:
+  image: docker:19.03.12
   stage: build
   script:
   - docker build -t my_homepage .
 
 push:
+  image: docker:19.03.12
   stage: push
   script:
   - docker tag my_homepage $REPO/my_homepage:$TAG