Fixed path in resource_string to use package for compatibility with older versions

[manan-memon]

The issue with using the __name__ variable while reading files via the importlib-resource library in older versions (e.g., 3.1.2) results in the following error:

get_package raises TypeError('{!r} is not a package'.format(package))
TypeError: 'h5pxblock.h5pxblock' is not a package

This PR updates the reference to __package__ instead of __name__ to ensure compatibility with older versions of the library.

Changes have been tested on both versions 3.1.2 and 6.4.5 (latest) of importlib-resources and are working correctly.

[ziafazal]

👍