[Ext] The link to boltztrap is not valid anymore

[DanielYang59]

I was trying to enable boltztrap in CI test, and found the URL is not valid anymore it appears:

pymatgen/src/pymatgen/electronic_structure/boltztrap.py

Lines 1 to 17 in 35b1f44

	"""This module provides classes to run and analyze boltztrap on pymatgen band
	structure objects. Boltztrap is a software interpolating band structures and
	computing materials properties from this band structure using Boltzmann
	semi-classical transport theory.
	Boltztrap has been developed by Georg Madsen.
	http://www.icams.de/content/research/software-development/boltztrap/
	You need version 1.2.3 or higher
	References are:
	Madsen, G. K. H., and Singh, D. J. (2006).
	BoltzTraP. A code for calculating band-structure dependent quantities.
	Computer Physics Communications, 175, 67-71
	"""

Also the same one in the requires decorator:

pymatgen/src/pymatgen/electronic_structure/boltztrap.py

Lines 62 to 72 in 35b1f44

	class BoltztrapRunner(MSONable):
	"""This class is used to run Boltztrap on a band structure object."""
	@requires(
	which("x_trans"),
	"BoltztrapRunner requires the executables 'x_trans' to be in PATH. Please download "
	"Boltztrap at http://www.icams.de/content/research/software-development/boltztrap/ "
	"and follow the instructions in the README to compile Bolztrap accordingly. "
	"Then add x_trans to your path",
	)
	def __init__(

However this mirror from TU Wien seems to be working, and I could get the "latest" v1.2.5 (released around 2017).