- fix source url

- update to 2.0.0:
* Add support for 384- and 512-bit elliptic curve groups in ECDSA
key types (aka ecdsa-sha2-nistp384 / ecdsa-sha2-nistp521).
* Due to an earlier bugfix, less-specific Host blocks' ProxyCommand
values were overriding ProxyCommand none in more-specific Host
blocks. This has been fixed in a backwards compatible manner (i.e.
ProxyCommand none continues to appear as a total lack of any
proxycommand key in parsed config structures).
* Fix a backwards incompatibility issue that cropped up in
SFTPFile.prefetch <~paramiko.sftp_file.prefetch> re: the
erroneously non-optional file_size parameter. Should only affect
users who manually call prefetch.
* Replace PyCrypto with the Python Cryptographic Authority (PyCA)
'Cryptography' library suite. This improves security,
installability, and performance; adds PyPy support; and much more.
* Fix stalled/hung SFTP downloads by cleaning up some threading lock
issues.
* Fix a Python 3 compatibility issue when handling two-factor
authentication.
* Clean up setup.py to always use setuptools, not doing so was a
historical artifact from bygone days.
* Update the module in charge of handling SSH moduli so it's
consistent with OpenSSH behavior re: prime number selection.
* Fix up ~paramiko.ssh_exception.NoValidConnectionsError so it
pickles correctly, and fix a related Python 3 compatibility issue.
* Update to jaraco.windows 3.4.1 to fix some errors related to
ctypes on Windows platforms.
* Annotate some public attributes on ~paramiko.channel.Channel such