Merge #1654

1654: Ensure that the rendered file ends with newline in order to make `pos… r=mergify[bot] a=tremlin

## What type of PR?

Bugfix

## What does this PR do?

This fixes #1580 

### Related issue(s)
- closes #1580

## Prerequistes
Before we can consider review and merge, please make sure the following list is done and checked.
If an entry in not applicable, you can check it or remove it from the list.


Co-authored-by: Thomas Rehn <thomas.rehn@initos.com>

core/postfix/conf/main.cf

@@ -126,3 +126,5 @@ milter_default_action = tempfail
 ###############
 # Extra Settings
 ###############
+{# Ensure that the rendered file ends with newline in order to make `postconf` work correctly #}
+{{- "\n" }}