Update for netmiko 4.x

[pszulczewski]

Contains:

• necessary updates related to netmiko to remove deprecated delay_factor in favor of read_timeout.
  Current delay_factor values have been recalculated accordingly to compat_timeout
  https://github.com/ktbyers/netmiko/blob/6bbee5fad8de1557af4ae32d98e98635e0392ae3/netmiko/base_connection.py#L1721

calc_old_timeout(
                max_loops=None,
                delay_factor=3,
                loop_delay=0.2,
                old_timeout=100,
            )
300.0

calc_old_timeout(
                max_loops=None,
                delay_factor=20,
                loop_delay=0.2,
                old_timeout=100,
            )
2000.0

calc_old_timeout(
                max_loops=500,
                delay_factor=30,
                loop_delay=0.2,
                old_timeout=3600,
            )
3000.0

fast_cli is not used anymore with read_timeout, so respective properties have been removed.
Method signatures have changed, delay_factor has been replaced with read_timeout, this is a braking change.

• fix to nxos_device kwargs, which were failing with nornir-nautobot inventory.

• pylint updates, pylint has been re-enabled.

[pszulczewski]

This PR has been tested for software upgrade against physical devices.

• cisco_ios Catalyst 3500 and Cisco ISR4351/K9 for both: install_mode and regular mode.
• cisco_nxos Cisco N9K-C9332C

Tested methods:

• save()
• file_copy()
• install_os()

[jeffkala]

From what I can tell I'm good with all of this.