python3-packaging: upgrade 20.4 -> 20.8

python3-packaging: upgrade 20.4 -> 20.8

Upstream release notes:
'''
* 20.8 - 2020-12-11
  - Revert back to setuptools for compatibility purposes for some Linux
    distros (:issue:`363`)
  - Do not insert an underscore in wheel tags when the interpreter version
    number is more than 2 digits (:issue:`372`)

* 20.7 - 2020-11-28
  - No unreleased changes.

* 20.6 - 2020-11-28
  - Note:
    This release was subsequently yanked, and these changes were included in
    20.7.

  - Fix flit configuration, to include LICENSE files (:issue:`357`)
  - Make intel a recognized CPU architecture for the universal macOS
    platform tag (:issue:`361`)
  - Add some missing type hints to packaging.requirements (issue:350)

* 20.5 - 2020-11-27
  - Officially support Python 3.9 (:issue:`343`)
  - Deprecate the LegacyVersion and LegacySpecifier classes (:issue:`321`)
  - Handle OSError on non-dynamic executables when attempting to resolve the
    glibc version string.
"""

Signed-off-by: Tim Orling <timothy.t.orling@linux.intel.com>