Description of problem:
Memory leak[1] in underlying ultrajson library inside ceilometer-notification

Version-Release number of selected component (if applicable):
16.1, 16.1.4 latest container image (16.1-51 at the time of writing [2]).

How reproducible:
See https://bugzilla.redhat.com/show_bug.cgi?id=1939112

Steps to Reproduce:
See https://bugzilla.redhat.com/show_bug.cgi?id=1939112

Actual results:
Controllers' memory usage keeps increasing due to above mentioned memory leak.

Expected results:
Memory should be reclaimed, and no memory usage constant increase should be seen on the Controller nodes

Additional info:

PR #394[1] is not contained in ultrajson 2.0.0, used by latest ceilometer image

from [2]
~~~
python3-ujson-2.0-0.1.20170206git2f1d487.el8ost.7.x86_64
~~~

but it is contained in 2.0.3 [4]
~~~
 $ git tag --contains 92c57b421052b146e4f2dfce9386c7cf13241091 | grep 2.0
2.0.3 <===
3.2.0
~~~

Need to bump ultrajson version to at least 2.0.3


[1] https://github.com/ultrajson/ultrajson/pull/394/commits/92c57b421052b146e4f2dfce9386c7cf13241091
[2] https://catalog.redhat.com/software/containers/rhosp-rhel8/openstack-ceilometer-notification/5de6af84d70cc51644a56d7b?tag=16.1-51&push_date=1600264861000&container-tabs=packages
[3] https://github.com/ultrajson/ultrajson/releases/tag/2.0.0
[4] https://github.com/ultrajson/ultrajson/releases/tag/2.0.3