fix test_case import bug

nac3core/src/typecheck/expression_inference.rs

@@ -451,6 +451,8 @@ pub mod test {
 
     use crate::typecheck::{symbol_resolver::SymbolResolver, symbol_resolver::*, location::*};
     use rustpython_parser::ast::Expr;
+    
+    #[cfg(test)]
     use test_case::test_case; // FIXME
     use super::*;