When running `ninja gimp30-windows-installer-pot`, we had this error:
```
[0/2] Running external command gimp30-windows-installer-pot
/usr/bin/xgettext: warning: ITS rule file 'gimp-ms-installer-config.its' does not exist; check your gettext installation
/usr/bin/xgettext: warning: file 'build/windows/installer/lang/setup.isl.xml.in' extension 'xml' is unknown; will try C
```