fix postgres variables

.gitlab-ci.yml

@@ -36,7 +36,10 @@ test sqlite to postgres:
     - "${CI_PROJECT_DIR}/signaldctl db-move postgresql://postgres@postgres/signald"
     - SIGNALD_DATABASE_URI=postgresql://postgres@postgres/signald signald --migrate-data
   services:
-    - postgres:latest
+    - name: postgres:latest
+      alias: postgres
+      variables:
+        POSTGRES_HOST_AUTH_METHOD: trust
 
 .build:
   stage: build