arrow

ARROW-9600: [Rust] pin proc macro

The previous PR that was merged for this did not correctly pin the version and did not check in the corresponding generated code for that version.

We need to use `=1.0.18` to pin an exact version since `1.0.18` means 1.0.18 or later.

https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html

Closes #7893 from andygrove/pin-proc-macro

Authored-by: Andy Grove <andygrove@nvidia.com>
Signed-off-by: Andy Grove <andygrove73@gmail.com>