Support for postgres 0.16.0-rc.2 (or 0.16)

[SitiSchu]

Currently when trying to use this crate with postgres = "0.16.0-rc.2" the example on Enums will error with

error: cannot find macro `to_sql_checked!` in this scope
 --> src/main.rs:6:17
  |
6 | #[derive(Debug, ToSql, FromSql)]

  |                 ^^^^^
error[E0726]: implicit elided lifetime not allowed here
 --> src/main.rs:6:24
  |
6 | #[derive(Debug, ToSql, FromSql)]
  |                        ^^^^^^^- help: indicate the anonymous lifetime: `<'_>`

Are there any plans to support postgres 0.16.0-rc.2 right now or will support be added when postgres 0.16 is released(or would this issue be better suited on the postgres repo itself) ?

[SitiSchu]

Ok looks like the first error is fixed by sfackler/rust-postgres@c0fcf34 and the second is fixed by #15