Release 0.3.1

[Hoverbear]

Release 0.3.1, a bugfix release.

Release notes:

---

v0.3.1

Upgrading

Please make sure to run cargo install cargo-pgx and update all the pgx extension Cargo.toml's pgx* versions to 0.3.1.

What's Changed

• Fix: We correctly use the right fcinfo ident if it's renamed in a #[pg_extern]. (Use correctly spanned fcinfo #433)
• We repaired some Cargo.toml metadata. (Repair metadata links in Cargo.tomls #434)