Raise libsqlite3-sys dependency from 0.30 to 0.31

[dtolnay]

This makes it possible to use sqlx and the most recent versions of the cargo crate in the same dependency graph. Cargo depends on rusqlite 0.33 which uses libsqlite3-sys 0.31. Without this PR, this dependency graph doesn't work.

error: failed to select a version for `libsqlite3-sys`.
    ... required by package `sqlx-sqlite v0.8.5`
    ... which satisfies dependency `sqlx-sqlite = "=0.8.5"` of package `sqlx v0.8.5`
    ... which satisfies dependency `sqlx = "^0.8.5"` of package `repro v0.0.0`
versions that meet the requirements `^0.30.1` are: 0.30.1

the package `libsqlite3-sys` links to the native library `sqlite3`, but it conflicts with a previous package which links to `sqlite3` as well:
package `libsqlite3-sys v0.31.0`
    ... which satisfies dependency `libsqlite3-sys = "^0.31.0"` of package `rusqlite v0.33.0`
    ... which satisfies dependency `rusqlite = "^0.33.0"` of package `cargo v0.87.1`
    ... which satisfies dependency `cargo = "^0.87"` of package `repro v0.0.0`
Only one package in the dependency graph may specify the same links value. This helps ensure that only one copy of a native library is linked in the final binary. Try to adjust your dependencies so that only one package uses the `links = "sqlite3"` value. For more information, see https://doc.rust-lang.org/cargo/reference/resolver.html#links.

failed to select a version for `libsqlite3-sys` which could resolve this conflict

Is this a breaking change?

The libsqlite3-sys update: no, previous precedent is that these are semver-exempt and anyone using libsqlite3-sys through some other dependency needs to have pinned their sqlx version and be updating in lockstep.

https://github.com/launchbadge/sqlx/blob/91d26bad4d5e2b05fab1c86d0fbe11586d30f29d/CHANGELOG.md#L888-L890

However, for this specific update, libsqlite3-sys requires a version of bindgen that only supports Rust 1.82+, and sqlx considers this a breaking change.

https://github.com/launchbadge/sqlx/blob/91d26bad4d5e2b05fab1c86d0fbe11586d30f29d/FAQ.md#L23-L24

If a new major version of sqlx is not imminent, I am still interested in libsqlite3-sys 0.31 in sqlx 0.8 and can make it not a breaking change by improving bindgen to generate Rust 1.78-compatible code when run by a toolchain older than 1.82.