Trailing comma breaks haxe versions under 4.3

[Geokureli]

https://github.com/HaxeFoundation/hscript/blob/master/hscript/Parser.hx#L880-L881 is causing the following error in my CI:

/home/runner/haxe/haxelib/hscript/git/hscript/Parser.hx:881: characters 5-6 : Unexpected )

I know 4.2 is quite old, but this seems like an easy enough change

[tobil4sk]

Aside from fixing the syntax issue, it would be good to also add 4.2 to the CI so this is caught in future