security/py-netmiko: Update to 2.3.0

• Pacify portlint [1]
• Switch to GitHub to enable test target [2]

Notable changes since 2.1.1:

• Add support for new platforms:
  • Apresia Systems AEOS
  • Citrix Netscaler
  • Dell EMC Isilon, Dell OS10 and DNOS6
  • IP Infusion OcNOS
  • RAD ETX
• Add fast_cli mode to improve performance
• Add support for a session_log
• Add Paramiko pkey, auth_timeout and passphrase support

Changelog:

https://github.com/ktbyers/netmiko/releases/tag/v2.3.0

PR: 236036
Submitted by: John W. O'Brien <john@saltant.com> [1]
Reviewed by: koobs [2]
Approved by: miwi (mentor)
Differential Revision: https://reviews.freebsd.org/D19361