gh-128217: Validate the normalized_environment variable instead of the similarly named function (GH-128220)

(cherry picked from commit 3ddd70ceaa)

Co-authored-by: Sergey Muraviov <smurav@mail.ru>

Modules/_winapi.c

@@ -1048,7 +1048,7 @@ getenvironment(PyObject* environment)
     }
 
     normalized_environment = normalize_environment(environment);
-    if (normalize_environment == NULL) {
+    if (normalized_environment == NULL) {
         return NULL;
     }