modernize changelog management in packaging

[dhellmann]

Building packages produces this warning:

[pbr] Generating ChangeLog
/Users/dhellmann/Envs/virtualenvwrapper/lib/python3.10/site-packages/setuptools/command/easy_install.py:144: EasyInstallDeprecationWarning: easy_install command is deprecated. Use build and pip and other standards-based tools.
  warnings.warn(
/Users/dhellmann/Envs/virtualenvwrapper/lib/python3.10/site-packages/setuptools/command/install.py:34: SetuptoolsDeprecationWarning: setup.py install is deprecated. Use build and pip and other standards-based tools.

[dhellmann]

Fixing this one may mean moving away from pbr, although explicitly installing 5.11.1 does eliminate the warning so I'm not sure.