Allow Path objects in MGXSLibrary.export_to_hdf5 (#3608)

Co-authored-by: Paul Romano <paul.k.romano@gmail.com>

Author: shimwell

openmc/mgxs_library.py

@@ -11,7 +11,7 @@
 import openmc.mgxs
 from openmc.mgxs import SCATTER_TABULAR, SCATTER_LEGENDRE, SCATTER_HISTOGRAM
 from .checkvalue import check_type, check_value, check_greater_than, \
-    check_iterable_type, check_less_than, check_filetype_version
+    check_iterable_type, check_less_than, check_filetype_version, PathLike
 
 ROOM_TEMPERATURE_KELVIN = 294.0
 
@@ -2506,15 +2506,15 @@ def export_to_hdf5(self, filename='mgxs.h5', libver='earliest'):
 
         Parameters
         ----------
-        filename : str
+        filename : str or PathLike
             Filename of file, default is mgxs.h5.
         libver : {'earliest', 'latest'}
             Compatibility mode for the HDF5 file. 'latest' will produce files
             that are less backwards compatible but have performance benefits.
 
         """
 
-        check_type('filename', filename, str)
+        check_type('filename', filename, PathLike)
 
         # Create and write to the HDF5 file
         file = h5py.File(filename, "w", libver=libver)