style: let taplo order the workspace dependency entry

`taplo format --check` runs over the whole workspace in CI, not over the two
manifests I had checked. It sorts the `[workspace.dependencies]` table, so
`postcard` belongs in alphabetical position inside the
external-dependencies block rather than immediately after its comment. Local
checking was narrower than the CI command, which is why this only surfaced
there.

Signed-off-by: discord9 <discord9@163.com>

Cargo.toml

@@ -99,7 +99,6 @@ rust.unexpected_cfgs = { level = "warn", check-cfg = ['cfg(tokio_unstable)'] }
 # for the inherited dependency but cannot do the reverse (override from true to false).
 #
 # See for more detaiils: https://github.com/rust-lang/cargo/issues/11329
-postcard = { version = "1.1.3", default-features = false, features = ["alloc", "use-std"] }
 ahash = { version = "0.8", features = ["compile-time-rng"] }
 aquamarine = "0.6"
 arrow = { version = "=59.2.0", features = ["prettyprint"] }
@@ -111,6 +110,7 @@ arrow-schema = { version = "=59.2.0", features = ["serde"] }
 arrow-select = "=59.2.0"
 async-stream = "0.3"
 async-trait = "0.1"
+postcard = { version = "1.1.3", default-features = false, features = ["alloc", "use-std"] }
 # Remember to update axum-extra, axum-macros when updating axum
 axum = "0.8"
 axum-extra = "0.10"