Re-exporting `semver`?

[8573]

Like camino, semver is in cargo_metadata's API, but, unlike with camino, cargo_metadata does not re-export the version of semver that it uses. I suggest that cargo_metadata also re-export semver so that users can be sure of using the same version cargo_metadata uses.

I could file a PR, but

 pub use camino;
-pub use semver::{Version, VersionReq};
+pub use semver::{self, Version, VersionReq};

is such a simple change that I figure handling a PR would be more work for you. :-)

(In case it matters, I dedicate the above patch under CC0-1.0.)

[UebelAndre]

1b4aea8 seems to be a followup change.