gitlab: add missing newlines (#309)

A couple testdata files had missing newlines, rather than go back and
forth again on the PR I'm just doing it myself.

Author: braydonk

internal/gitlab/testdata/changed_line/formatted.yaml

@@ -15,4 +15,4 @@ services:
     image: postgres:14
     environment:
       - POSTGRES_DB=myapp
-      - POSTGRES_USER=admin
+      - POSTGRES_USER=admin

internal/gitlab/testdata/changed_line/original.yaml

@@ -15,4 +15,4 @@ services:
     image: postgres:14
     environment:
       - POSTGRES_DB=myapp
-      - POSTGRES_USER=admin
+      - POSTGRES_USER=admin