bug fixing : should be main not master

.gitlab-ci.yml

@@ -77,12 +77,11 @@ django-tests:
     - python3 manage.py test
 
 
-
 deploy-railway:
   stage: deploy
   image: ubuntu
   only:
-    - master
+    - main
   script:
     - apt-get clean
     - apt-get -o Acquire::ForceIPv4=true update