feat: enhance assert casting

crates/erg_compiler/hir.rs

@@ -1407,6 +1407,7 @@ impl Call {
             "import" => Some(OperationKind::Import),
             "pyimport" | "py" | "__import__" => Some(OperationKind::PyImport),
             "Del" => Some(OperationKind::Del),
+            "assert" => Some(OperationKind::Assert),
             _ => {
                 if self.obj.ref_t().is_callable() {
                     match self.attr_name.as_ref().map(|i| &i.inspect()[..]) {