btrfs-progs: libbtrfsutil: use package_data member for header files

[BUG]
Currently with python3.12, the python bindding will always result the
following warning:

    [PY]     libbtrfsutil
/usr/lib/python3.12/site-packages/setuptools/_distutils/extension.py:134: UserWarning: Unknown Extension options: 'headers'
  warnings.warn(msg)

[CAUSE]
In the setup.py which specifies the files to be included into the
package, we use setuptools::Extension to specify the file lists and
include paths.

But there is no handling of Extension::headers member, thus resulting
the above warning.

[FIX]
Not an expert in python, but other packages like cffi are all using
`package_data` to include the headers, so just follow them to use
`package_data` member for headers.

Fixes: 87c3fb5 ("libbtrfsutil: update python setup.py for distribution")
Signed-off-by: Qu Wenruo <wqu@suse.com>

libbtrfsutil/python/setup.py

@@ -97,9 +97,6 @@ def run(self):
         'qgroup.c',
         'subvolume.c',
     ],
-    headers=[
-        'btrfsutilpy.h'
-    ],
     include_dirs=['..'],
     library_dirs=['../..'],
     libraries=['btrfsutil'],
@@ -113,6 +110,7 @@ def run(self):
     description='Library for managing Btrfs filesystems',
     long_description=open('../README.md').read(),
     long_description_content_type='text/markdown',
+    package_data = { "btrfstuil" : [ "btrfsutilpy.h" ] },
     url='https://github.com/kdave/btrfs-progs',
     license='LGPLv2+',
     cmdclass={'build_ext': my_build_ext},