updateIntermediary doesn't support v2 mappings

[Juuxel]

It uses the v1 mapping parser, so it will crash if the intermediary is a tinyv2 file.

java.io.IOException: Invalid mapping version!
        at net.fabricmc.mappings.TinyMappings.<init>(TinyMappings.java:119)
        at net.fabricmc.mappings.MappingsProvider.readTinyMappings(MappingsProvider.java:36)
        at net.fabricmc.mappings.MappingsProvider.readTinyMappings(MappingsProvider.java:32)
        at net.fabricmc.stitch.commands.GenState.prepareUpdate(GenState.java:465)
        at net.fabricmc.stitch.commands.CommandUpdateIntermediary.run(CommandUpdateIntermediary.java:62)
        at net.fabricmc.stitch.Main.main(Main.java:71)