Upgrade pysnmp to 4.3.5

[fabaff]

4.3.5

• The getNext() and getBulk() calls of Twisted interface. Now support ignoreNonIncreasingOid option.
• TextualConvention is now a new-style class.
• Fix to accidentally reset error-status when building confirmed class SNMPv1 PDU.
• Fix to possible infinite recursion in TextualConvention.prettyIn().
• Fixed crash when attempting to report unsupported request/notification PDU back to sender.

Tested with the following configuration:

sensor:
  - platform: snmp
    name: SNMP TEST String
    host: demo.snmplabs.com
    community: public
    baseoid: 1.3.6.1.4.1.2021.10.1.3.1
    unit_of_measurement: "load"

[mention-bot]

@fabaff, thanks for your PR! By analyzing the history of the files in this pull request, we identified @kellerza, @mKeRix and @balloob to be potential reviewers.