[pre-commit.ci] Auto fixes from pre-commit.com hooks.

Author: pre-commit-ci[bot]

src/pybind11-utils/include/pybind11_utils/smart_variant_wrapper.h

@@ -91,7 +91,7 @@ namespace mo2::python {
         };
 
         template <class R, class C, class... Args>
-        struct function_signature<R (C::*)(Args...)&> {
+        struct function_signature<R (C::*)(Args...) &> {
             using type = R(C*, Args...);
         };