set CFBundleDevelopmentRegion to "en" and set CFBundleAllowMixedLocalizations

set CFBundleDevelopmentRegion to "en" and set CFBundleAllowMixedLocalizations

according to [1] the value should be a ISO 639-1 code, so let's correct
it

`CFBundleAllowMixedLocalizations` is the most interesting one: with this
being set the reported QLocale will no longer be English as well

(this also bumps the version info to 2025 :D)

[1]: https://developer.apple.com/documentation/bundleresources/information-property-list/cfbundledevelopmentregion

Signed-off-by: Jyrki Gadinger <nilsding@nilsding.org>