Minimal example now results in a `StackOverflowError` as of 0.6.0

[ckipp01]

In the projects that I'm using mainargs in updating to 0.6.0 results in a StackOverflowError. You can reproduce this with a minimized version of the example in the readme.

//> using scala 3.3.1
//> using dep com.lihaoyi::mainargs:0.6.0

package testhello
import mainargs.{main, arg, ParserForMethods, Flag}

object Main {
  @main
  def run(
      @arg(short = 'f')
      foo: String
  ) = {
    println(foo)
  }
  def main(args: Array[String]): Unit = ParserForMethods(this).runOrExit(args)

}

This will blow up with:

Exception in thread "main" java.lang.StackOverflowError
        at mainargs.ParserForMethods.runEither(Parser.scala:216)
        at mainargs.ParserForMethods.runEither(Parser.scala:216)
        at mainargs.ParserForMethods.runEither(Parser.scala:216)
        at mainargs.ParserForMethods.runEither(Parser.scala:216)
        at mainargs.ParserForMethods.runEither(Parser.scala:216)
        at mainargs.ParserForMethods.runEither(Parser.scala:216)
        at mainargs.ParserForMethods.runEither(Parser.scala:216)
        at mainargs.ParserForMethods.runEither(Parser.scala:216)
...

When you bump down to 0.5.4, everything works as expected.