fixup migration guide examples

guide/src/migration.md

@@ -223,7 +223,8 @@ was not needed in the first place.
 
 Before:
 
-```rust,ignore
+```rust
+# #[cfg(not(Py_GIL_DISABLED))] {
 # use pyo3::prelude::*;
 use pyo3::sync::GILProtected;
 use pyo3::types::{PyDict, PyNone};
@@ -234,12 +235,13 @@ static OBJECTS: GILProtected<RefCell<Vec<Py<PyDict>>>> =
 
 fn main() {
     Python::with_gil(|py: Python| {
-        let d = PyDict::new(py);
         // stand-in for something that executes arbitrary python code
+        let d = PyDict::new(py);
         d.set_item(PyNone::get(py), PyNone::get(py)).unwrap();
         OBJECTS.get(py).borrow_mut().push(d.unbind());
     });
 }
+# }
 ```
 
 After:
@@ -262,8 +264,8 @@ static OBJECTS: Mutex<Vec<Py<PyDict>>> = Mutex::new(Vec::new());
 
 fn main() {
     Python::with_gil(|py| {
-        let d = PyDict::new(py);
         // stand-in for something that executes arbitrary python code
+        let d = PyDict::new(py);
         d.set_item(PyNone::get(py), PyNone::get(py)).unwrap();
         #[cfg(not(Py_GIL_DISABLED))]
         OBJECTS.get(py).borrow_mut().push(d.unbind());