py36-setuptools is broken on GitHub CI

[catap (Kirill A. Korinsky)]

An attempt to update py-hypothesis ​https://github.com/macports/macports-ports/pull/15598 discovered an issue inside py36-setuptools

DEBUG: system:  cd "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0" && /opt/local/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6 -m build --wheel --no-isolation --outdir /opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work --skip-dependency-check 
  Traceback (most recent call last):
    File "/opt/local/share/py-bootstrap-modules/pep517/in_process/_in_process.py", line 363, in <module>
      main()
    File "/opt/local/share/py-bootstrap-modules/pep517/in_process/_in_process.py", line 345, in main
      json_out['return_val'] = hook(**hook_input['kwargs'])
    File "/opt/local/share/py-bootstrap-modules/pep517/in_process/_in_process.py", line 262, in build_wheel
      metadata_directory)
    File "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0/setuptools/build_meta.py", line 231, in build_wheel
      wheel_directory, config_settings)
    File "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0/setuptools/build_meta.py", line 215, in _build_with_temp_dir
      self.run_setup()
    File "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0/setuptools/build_meta.py", line 158, in run_setup
      exec(compile(code, __file__, 'exec'), locals())
    File "setup.py", line 87, in <module>
      dist = setuptools.setup(**setup_params)
    File "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0/setuptools/__init__.py", line 153, in setup
      return distutils.core.setup(**attrs)
    File "/opt/local/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/distutils/core.py", line 108, in setup
      _setup_distribution = dist = klass(attrs)
    File "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0/setuptools/dist.py", line 463, in __init__
      for k, v in attrs.items()
    File "/opt/local/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/distutils/dist.py", line 281, in __init__
      self.finalize_options()
    File "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0/setuptools/dist.py", line 836, in finalize_options
      for ep in sorted(loaded, key=by_order):
    File "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0/setuptools/dist.py", line 835, in <lambda>
      loaded = map(lambda e: e.load(), filtered)
    File "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0/pkg_resources/__init__.py", line 2464, in load
      self.require(*args, **kwargs)
    File "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0/pkg_resources/__init__.py", line 2487, in require
      items = working_set.resolve(reqs, env, installer, extras=self.extras)
    File "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0/pkg_resources/__init__.py", line 777, in resolve
      raise DistributionNotFound(req, requirers)
  pkg_resources.DistributionNotFound: The 'tomli>=1.0.0' distribution was not found and is required by the application
  * Building wheel...
  
  ERROR Backend subprocess exited when trying to invoke build_wheel
  Command failed:  cd "/opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work/setuptools-59.6.0" && /opt/local/Library/Frameworks/Python.framework/Versions/3.6/bin/python3.6 -m build --wheel --no-isolation --outdir /opt/local/var/macports/build/_Users_runner_work_macports-ports_macports-ports_ports_python_py-setuptools/py36-setuptools/work --skip-dependency-check 
  Exit code: 1
  Error: Failed to build py36-setuptools: command execution failed

[jmroot (Joshua Root)]

This is at least two bugs: why did CI build setuptools from source instead of using the binary? And why wasn't it installed in the correct step along with the rest of the dependencies?

 Installing 3 dependencies of py36-hypothesis:
  python36 +optimizations
  py36-attrs 
  py36-sortedcontainers 
  
  Installing dependency (1 of 3) 'python36' with variants '+optimizations' ... [OK]
  Installing dependency (2 of 3) 'py36-attrs' with variants '' ... [OK]
  Installing dependency (3 of 3) 'py36-sortedcontainers' with variants '' ... [OK]

[jmroot (Joshua Root)]

Second bug is taken care of by [308a4dc82148e26077ca66724f63009e2cfd0cec/mpbb].

[jmroot (Joshua Root)]

In a541192665a08e682abdaec137012d32694d6436/macports-ports (master):

py36-setuptools: add tomli build dep

Fixes: #65611