Use Py_DECREF after PyObject_CallObject call (#6781)

`PyObject_CallObject` returns new reference:
https://docs.python.org/3/c-api/call.html#c.PyObject_CallObject.

Signed-off-by: Anatoly Myachev <[email protected]>

Author: anmyachev

third_party/amd/backend/driver.py

@@ -441,6 +441,7 @@ def format_of(ty):
     Py_DECREF(args);
     if (!ret)
       return NULL;
+    Py_DECREF(ret);
   }}
 
 
@@ -454,6 +455,7 @@ def format_of(ty):
     Py_DECREF(args);
     if (!ret)
       return NULL;
+    Py_DECREF(ret);
   }}
 
   if(PyErr_Occurred()) {{

third_party/nvidia/backend/driver.py

@@ -472,6 +472,7 @@ def format_of(ty):
     Py_DECREF(args);
     if (!ret)
       return NULL;
+    Py_DECREF(ret);
   }}
 
   CUdeviceptr global_scratch = 0;
@@ -499,7 +500,7 @@ def format_of(ty):
     Py_DECREF(args);
     if (!ret)
       return NULL;
-
+    Py_DECREF(ret);
   }}
 
   Py_RETURN_NONE;