Remove remaining references to tigris.org

[ryandesign]

The tigris.org service shut down in 2020 (as previously reported in #8, #13, #14) but numerous references to this domain remain within the cvs2svn codebase, for example:

cvs2svn/COPYING

Lines 6 to 7 in 8cd4323

	This is version 1 of this license. It is also available online at
	http://subversion.tigris.org/license-1.html. If newer versions of

cvs2svn/setup.py

Lines 23 to 34 in 8cd4323

	author_email = "dev@cvs2svn.tigris.org",
	url = "http://cvs2svn.tigris.org/",
	download_url = "http://cvs2svn.tigris.org/servlets/ProjectDocumentList?folderID=2976",
	license = "Apache-style",
	long_description = """\
	cvs2svn_ is a tool for migrating a CVS repository to Subversion_, git_,
	Bazaar_, or Mercurial_. The main design goals are robustness and 100% data
	preservation. cvs2svn can convert just about any CVS repository we've ever
	seen, including gcc, Mozilla, FreeBSD, KDE, GNOME...
	.. _cvs2svn: http://cvs2svn.tigris.org/
	.. _Subversion: http://svn.tigris.org/

cvs2svn/doc/making-releases.txt

Lines 12 to 17 in 8cd4323

	Creating the release:
	1. If this is an A.B.0 release, make a branch:
	svn copy http://cvs2svn.tigris.org/svn/cvs2svn/trunk \
	http://cvs2svn.tigris.org/svn/cvs2svn/branches/A.B.x
	and then increment the -dev VERSION in cvs2svn_lib/version.py on
	trunk.

Please remove all remaining references to this domain from your project, except where it is specifically to point out where the project used to be hosted.