Revert file rename from T59773 fix

Mixing file rename with other changes should be avoided.

Using 'module_py_api' convention here
is in keeping with imbuf, idprop, blf & bmesh.
No reason for gpu to have a different convention.

source/blender/python/gpu/gpu_py_element.c

@@ -36,7 +36,7 @@
 #include "../generic/py_capi_utils.h"
 #include "../generic/python_utildefines.h"
 
-#include "gpu_py.h"
+#include "gpu_py_api.h"
 #include "gpu_py_element.h" /* own include */