deprecated warning when install package

[Philippe P.]

With the version of pip +21.1, when we install a package with pbr,

Installing collected packages: shaystack
  Attempting uninstall: shaystack
    Found existing installation: shaystack 0.0.1.dev682
    Uninstalling shaystack-0.0.1.dev682:
      Successfully uninstalled shaystack-0.0.1.dev682
  Running setup.py develop for shaystack
WARNING: Value for scheme.headers does not match. Please report this to <https://github.com/pypa/pip/issues/9617>
distutils: ~/miniconda3/envs/shaystack/include/python3.7m/UNKNOWN
sysconfig: ~/miniconda3/envs/shaystack/include/python3.7m
WARNING: Additional context:
user = False
home = None
root = None
prefix = None

It's because pbr use the deprecated disutils (See PEP-632 https://www.python.org/dev/peps/pep-0632/ )

https://stackoverflow.com/questions/67244301/warning-value-for-scheme-data-does-not-match-when-i-try-to-update-pip-or-inst/67250419#67250419

I find an import of disutils in pbr/core.py (See https://github.com/openstack/pbr/search?q=distutils)