Add python3 packaging module

As part of the effort to standardize our version comparison scheme,
https://gerrit.openbmc.org/c/openbmc/bmcweb/+/57407 needs this package
to be able to sort redfish schemas at build time.  This seems like a
pretty common and well supported package.

Add it to the docker image.

Tested: the aformentioned review passes CI when run locally.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Ifdb49cfacf4c6bf27fee882d08bdf469d32cc7a6
diff --git a/scripts/build-unit-test-docker b/scripts/build-unit-test-docker
index 153dd80..78e6471 100755
--- a/scripts/build-unit-test-docker
+++ b/scripts/build-unit-test-docker
@@ -826,6 +826,7 @@
 RUN pip3 install pycodestyle
 RUN pip3 install jsonschema
 RUN pip3 install meson==0.63.0
+RUN pip3 install packaging
 RUN pip3 install protobuf
 RUN pip3 install codespell
 RUN pip3 install requests