fix(generate): pass default optimization level in

`generate_parser_for_grammar`

Passing `empty` here causes some grammars (i.e. tree-sitter-cpp) to fail
to generate.

(cherry picked from commit 457eb295b7)

crates/generate/src/generate.rs

@@ -337,7 +337,7 @@ pub fn generate_parser_for_grammar(
         LANGUAGE_VERSION,
         semantic_version,
         None,
-        OptLevel::empty(),
+        OptLevel::default(),
     )?;
     Ok((input_grammar.name, parser.c_code))
 }