Fix malformed sflow packets DOS vector

Merge pull request from GHSA-9rpw-2h95-666c

NETDEV-5107: Fix malformed sflow packets DOS vector

v3.4.2

Add fixed length protobuf parameter

v3.4.1

Fix typo in kafka keying

v3.4.0

Added PPP and fixed IP flags decoding

v3.3.0

Fix go.mod issue with v3

Small fixes and reuse socket

• NetFlow v5 metrics
• Fix deadlock in decoder
• Add reuse socket in CLI

v3.1.0: Version 3

* NetFlow v5
* Change of protobuf:
  * Improved naming
  * Remove deprecated
* Kafka improvements (send by key)
* Cleanup and refactoring:
  * GoFlow + lite versions (only sFlow, IPFIX/NFv9 or NFv5)
  * Better formatter for output
  * Improved APIs for development and error handling
  * Tests!
* Comparison table (mapping) in the README
* Go mod
* Travis CI integration

Socket reuse update

Thanks to @kanocz, goflow supports reuse socket. This allow better performances when multithreading goflow recv queues (same socket).
May work only with sFlow since NetFlow v9/IPFIX templates require consistent hashing.

New fields update

New fields:

• TimeFlowStart / TimeFlowEnd
• IngressVrfID / EgressVrfID

Thanks @debugloop

Flow label update

Decodes IPv6 Flow label
Updated Sarama dependency (directly from Github)