Move alias from definitions in pipelines YAML

bitbucket-pipelines.yml

@@ -11,7 +11,12 @@ clone:
 
 
 definitions:
-  step: &unittest-python
+  services:
+    postgres:
+      image: postgres
+
+aliases:
+  - &unittest-python
     name: Unittest python server code
       caches:
       - pip
@@ -25,10 +30,6 @@ definitions:
       - export USE_AWS=False
       - pipenv install --dev --system
       - ./server/run_unittests_coverage.sh
-  services:
-    postgres:
-      image: postgres
-
 
 pipelines:
   default: