Removing pragma GCC -Wunused-but-set-parameter

Author: rwgk

include/pybind11/pybind11.h

@@ -32,7 +32,6 @@
 #  pragma warning(disable: 4505) // warning C4505: 'PySlice_GetIndicesEx': unreferenced local function has been removed (PyPy only)
 #elif defined(__GNUG__) && !defined(__clang__)
 #  pragma GCC diagnostic push
-#  pragma GCC diagnostic ignored "-Wunused-but-set-parameter"
 #  pragma GCC diagnostic ignored "-Wunused-but-set-variable"
 #  pragma GCC diagnostic ignored "-Wmissing-field-initializers"
 #  pragma GCC diagnostic ignored "-Wattributes"