### Summary

Our setuptools constrain in `pyproject.toml` (listed also in `setup.cfg`) is set to `>= 39.2.0` due to the minimum version available at the time on Ubuntu 18.04.

Now that we have a dependency on Python 3.9 as a minimum, that constraint no longer makes sense, as Python 3.9 is not available on 18.04, and the `dist-packages` `setuptools==39.2.0` compat between deadsnakes python3.9 is non-functional.

This would make Ubuntu 20.04 effectively the minimum supported controller.  The `dist-packages` `setuptools==45.2.0` is functional with the `python3.9` package, and works fine with our packaging.  

This doesn't really grant us anything, since we're waiting for the minimum to eventually be `51.0.0` so we can list the `entry_points` in `pyproject.toml`, but no need to list effectively a non-functional lower bounds. 

### Issue Type

Feature Idea

### Component Name

pyproject.toml

### Additional Information

<!--- Paste example playbooks or commands between quotes below -->
```yaml (paste below)

```


### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
"""
    This looks for all files which should be shipped in the sdist
    """
    
    ignore_patterns = (
        
        '.azure-pipelines/*',
        '.github/*',
        '.github/*/*',
        'changelogs/fragments/*',
        'hacking/backport/*',
        'hacking/azp/*',
        'hacking/tests/*',
        'hacking/ticket_stubs/*',
        'test/sanity/code-smell/botmeta.*',
        'test/sanity/code-smell/release-names.*',
        'test/results/.tmp/*',
        'test/results/.tmp/*/*',
        'test/results/.tmp/*/*/*',
        'test/results/.tmp/*/*/*/*',
        'test/results/.tmp/*/*/*/*/*',
        '.git*',
    )
    ignore_files = frozenset((
        
        'changelogs/config.yaml',
        'hacking/README.md',
        'hacking/ansible-profile',
        'hacking/cgroup_perf_recap_graph.py',
        'hacking/create_deprecated_issues.py',