Add \n to the end of the replay file

This is just to be nice to editors, that usually like having a `\n` at
the end of text files.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

.cookiecutter-replay.json

@@ -16,4 +16,4 @@
     "default_codeowners": "@frequenz-floss/python-sdk-team",
     "_template": "gh:frequenz-floss/frequenz-repo-config-python"
   }
-}
+}