Update rust-version (#362)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Leigh McCulloch <[email protected]>

Author: github-actions[bot]

cmd/soroban-cli/Cargo.toml

@@ -8,7 +8,7 @@ license = "Apache-2.0"
 readme = "README.md"
 version = "0.4.0"
 edition = "2021"
-rust-version = "1.66"
+rust-version = "1.67"
 autobins = false
 
 [[bin]]