PEP 788: Fix incorrect call to free (python#4725)

Author: ZeroIntensity

peps/pep-0788.rst

@@ -553,7 +553,6 @@ With this PEP, you would implement it like this:
             return -1;
         }
         int res = PyFile_WriteString(to_write, file);
-        free(to_write);
         if (res < 0) {
             PyErr_Print();
         }