final is now a reserved keyword in haxe 4+

[mastef]

Based on this change all : added final keyword (#6596) HaxeFoundation/haxe#6596 this code now breaks : https://github.com/HaxeFoundation/format/blob/master/format/abc/Reader.hx#L217-L225

The error produced is :
format/format/abc/Reader.hx:217: characters 4-7 : Missing variable identifier
format/format/abc/Reader.hx:217: characters 8-13 : Unexpected final
format/format/abc/Reader.hx:217: characters 8-13 : Unexpected final