[gimp/nielsdg/die-intltool-die] extensions: fix meson build after MR !653.

[Jehan <jehanp src gnome org>]

commit 671b547c7e744d328ffab0bd84bf5c338511a67e
Author: Jehan <jehan girinstud io>
Date:   Fri Jun 24 22:43:13 2022 +0200

    extensions: fix meson build after MR !653.
    
    On recent meson versions, it fixes this error:
    
    > extensions/goat-exercises/meson.build:108:0: ERROR: i18n.merge_file keyword argument 'output' was of 
type array[str] but should have been str
    
    As docs explains, 'output' only accepts one item in i18n.merge_file().
    
    This bug also happens on older meson (but there the reported error is a
    lot less useful as it doesn't mention local meson build code).

 extensions/goat-exercises/meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/extensions/goat-exercises/meson.build b/extensions/goat-exercises/meson.build
index 0ff2f2c160..09223625af 100644
--- a/extensions/goat-exercises/meson.build
+++ b/extensions/goat-exercises/meson.build
@@ -107,7 +107,7 @@ appdatafilein = configure_file(
 
 appdatafile = i18n.merge_file(
   input : [ appdatafilein, ],
-  output: [ appdatafilename, ],
+  output: appdatafilename,
   po_dir: po_plug_ins_dir,
   install: true,
   install_dir: gimpplugindir /  'extensions' / extension_name,