chore(deps): Resolve deprecation warning for chrono Date and ymd methods

[iamjpotts]

Does your PR solve an issue?

Resolves a deprecation warning caused by the chrono crate deprecating its Date type and the ymd method that returned a Date value.

Example of deprecation warning:

warning: use of deprecated method `sqlx::types::chrono::TimeZone::ymd`: use `with_ymd_and_hms()` instead
   --> tests/postgres/types.rs:355:67
    |
355 |             == FixedOffset::east_opt(60 * 60 * 6 + 1800).unwrap().ymd(2019, 1, 2).and_hms_micro_opt(5, 10, 20, 115100).unwrap()
    |                                                                   ^^^
    |
    = note: `#[warn(deprecated)]` on by default

Is this a breaking change?

No; only changes tests:

• Replace deprecated builder methods with newer ones
• Add -D warnings to RUSTFLAGS for postgres ci jobs, now that all of the compile warnings are resolved.

There is still a warning about cargo features, but that is not affected by -D warnings.