security/py-netmiko: Update to 3.1.0

Changelog:

New Platforms / Transports:

• D-Link DGS/DES
• WatchGuard Firebox
• Sophos SG Firewalls
• Huawei Telnet Support

Bug Fixes/Enhancements:

• Add cmd_verify argument to send_command
• Add global_cmd_verify argument to ConnectHandler

https://github.com/ktbyers/netmiko/releases/tag/v3.1.0

MFH: 2020Q2