refactor: remove the unnecessary sql converter (#72)

Author: ChunxuTang

rust/lance-graph/src/lib.rs

@@ -47,7 +47,6 @@ pub mod query_processor;
 pub mod semantic;
 pub mod simple_executor;
 pub mod source_catalog;
-pub mod sql_converter;
 
 /// Maximum allowed hops for variable-length relationship expansion (e.g., *1..N)
 pub const MAX_VARIABLE_LENGTH_HOPS: u32 = 20;