fix missing newline in ftl files

https://anki.tenderapp.com/discussions/beta-testing/1836-problem-with-new-translations

qt/ftl/addons.ftl

@@ -6,4 +6,4 @@ addons-failed-to-load =
     {$traceback}
 # Shown in the add-on configuration screen (Tools>Add-ons>Config), in the title bar
 addons-config-window-title = Configure '{$name}'
-addons-config-validation-error = There was a problem with the provided configuration: {$problem}
+addons-config-validation-error = There was a problem with the provided configuration: {$problem}

rslib/tests/support/ftl/templates/test.ftl

@@ -4,4 +4,4 @@ two-args-key = two args: {$one} and {$two}
 plural = You have {$hats ->
      [one]   1 hat
     *[other] {$hats} hats
-  }.
+  }.