Relax Upper Bound for swift-argument-parser
Relax Upper Bound for swift-argument-parser

Since we only rely on a narrow slice of this for a testing tool,
we don't really have the same version bounds issues that other packages
have. To enable broader adoption of swift-syntax, keep the lower bound
compatible with Apple's swift ecosystem, and the upper bound loose enough
for 3rd parties. Over time, we can continue to relax this upper bound as
we discover more clients.

Ultimately, it would be great if we could restrict the argument parser to
being a "private" dependency of this package since we don't actually depend
on it in a meaningful sense for the library targets here.

apple/swift-syntax,apple/swift-syntax,apple/swift-syntax