software/fluentd/test: adjust test for msgpack >= 1.0

As described in https://github.com/msgpack/msgpack-python#major-breaking-changes-in-msgpack-10
raw is False by default for unpacker so we receive strings, not bytes
4 jobs for fix/fluentd-msgpack-1.0 in 0 seconds
Status Job ID Name Coverage
  External
passed SlapOS.Eggs.UnitTest-TestRunner1.Python2

00:25:07

passed SlapOS.Eggs.UnitTest-TestRunner1.Python3

00:30:28

canceled SlapOS.SoftwareReleases.IntegrationTest-TestRunner1

01:11:16

passed Zodbtools.UnitTest-Master.ZODB4.Python2

00:00:38