Fix failing unit tests for new msgpack version

This fixes the failing unit tests with the newly msgpack
version.

Also depends on a requirements patch that bans pecan 1.4.0
that has broken gnocchi and hence ceilometer which uses
gnocchi as the default backend.

Task: 40652
Depends-on: https://review.opendev.org/746261
Change-Id: Id75b7d4004a50c588a22c7eeb46ad1d79ee7a189

ceilometer/publisher/udp.py

@@ -69,7 +69,7 @@ class UDPPublisher(publisher.ConfigPublisherBase):
                       "%(host)s:%(port)d", {'msg': msg, 'host': host,
                                             'port': port})
             try:
-                self.socket.sendto(msgpack.dumps(msg),
+                self.socket.sendto(msgpack.dumps(msg, use_bin_type=True),
                                    (self.host, self.port))
             except Exception as e:
                 LOG.warning(_("Unable to send sample over UDP"))

ceilometer/tests/unit/publisher/test_udp.py

@@ -125,7 +125,7 @@ class TestUDPPublisher(base.BaseTestCase):
         sent_counters = []
 
         for data, dest in self.data_sent:
-            counter = msgpack.loads(data, encoding="utf-8")
+            counter = msgpack.loads(data, raw=False)
             sent_counters.append(counter)
 
             # Check destination