[breaking for 0.4] Mark `MatchOptions` `#[non_exhaustive]`

[tgross35]

#144 mentioned adding a sort_paths: bool to MatchOptions, and it would be very nice to have a way to specify the root directory like python. To have forward compatibility with these kind of changes, we should make it #[non_exhaustive] with the next release.

Probably requires an MSRV bump, but the current version is far too old anyway.