ARROW-7797: [Release][Rust] Fix arrow-flight's version in datafusion …

…crate

After the release the version number got bumped except this one.

Closes #6383 from kszucs/cargo-fix and squashes the following commits:

660c448 <Krisztián Szűcs> Fix arrow-flight version

Authored-by: Krisztián Szűcs <szucs.krisztian@gmail.com>
Signed-off-by: Neal Richardson <neal.p.richardson@gmail.com>

rust/datafusion/Cargo.toml

@@ -61,7 +61,7 @@ prost = "0.6"
 tokio = { version = "0.2", features = ["macros"] }
 tonic = "0.1"
 flatbuffers = "0.6.0"
-arrow-flight = { path = "../arrow-flight", version = "0.16.0-SNAPSHOT" }
+arrow-flight = { path = "../arrow-flight", version = "1.0.0-SNAPSHOT" }
 
 [[bench]]
 name = "aggregate_query_sql"