py-cheroot: updated to 8.6.0

v8.6.0

Significant improvements:

- :issue:`384` via :pr:`385`, :pr:`406`: Exposed type stubs with
  annotations for public API -- by :user:`kasium`.

- :pr:`401` (related to the :pr:`352` effort): Started reusing the
  the ``expriration_interval`` setting in the low-level
  :py:func:`~select.select` invocation, effectively reducing the system
  load under the Windows OS when idle, that is noticeable on low-end
  hardware systems -- by :user:`MichaIng`.

Internal changes:

- Implemented a manual-trigger-based release workflow.
- Integrated publishing GitHub Releases into the workflow.
- Migrated the docs theme to `Furo <https://pradyunsg.me/furo>`__
  (created by :user:`pradyunsg`).
- Attempted to improve the stability of testing.
- Configured the CI to test the same distribution as will be shipped.
- Improved the linting setup and contributor checklists.
- Stopped running tests under Ubuntu 16.04.
- Tweaked the distribution packages metadata to satisfy strict checks.
- Implemented distribution build reproducibility using a pip constraints
  lock-file.
- Added per-environment lock-files into the tox test environments.

v8.5.2

- :issue:`358` via :pr:`359`: Fixed a regression from
  :pr:`199` that made the worker threads exit on invalid
  connection attempts and could make the whole server
  unresponsive once there was no workers left.
  -- by :user:`cameronbrunner`.

v8.5.1

- :cp-issue:`1873` via :pr:`340`: Resurrected an
  unintentionally removed feature of interrupting a server
  main thread by externally assigning an exception to the
  :py:meth:`HTTPServer.interrupt <cheroot.server.\
  HTTPServer.interrupt>` property -- by :user:`liamstask`.

- :pr:`350`: Fixed the incarnation of an earlier regression
  of not resetting the serving state
  on :py:data:`SIGINT` originally fixed by :pr:`322` and
  :pr:`331` but reintroduced by the changes in :pr:`311`
  -- by :user:`liamstask`.

v8.5.0

- :issue:`305` via :pr:`311`: In
  :py:class:`~cheroot.connections.ConnectionManager`,
  process connections as they become active rather than
  waiting for a ``tick`` event, addressing performance
  degradation introduced in v8.1.0 -- by :user:`liamstask`.

- :issue:`341` via :pr:`342`: Suppress legitimate OS errors
  expected on shutdown -- by :user:`webknjaz`.

v8.4.8

- :issue:`317` via :pr:`337`: Fixed a regression in
  8.4.5 where the connections dictionary would change
  size during iteration, leading to a :py:exc:`RuntimeError`
  raised in the logs -- by :user:`liamstask`.

v8.4.7

- :pr:`334`: Started filtering out TLS/SSL errors when
  the version requested by the client is unsupported
  -- by :user:`sanderjo` and :user:`Safihre`.

v8.4.6

- :issue:`328` via :pr:`322` and :pr:`331`: Fixed a
  regression introduced in the earlier refactoring in v8.4.4
  via :pr:`309` that caused the :py:meth:`~cheroot.server.\
  HTTPServer.serve` method to skip setting
  ``serving=False`` on :py:data:``SIGINT`` and
  :py:data:``SIGTERM`` -- by :user:`marc1n` and
  :user:`cristicbz`.

v8.4.5

- :issue:`312` via :pr:`313`: Fixed a regression introduced
  in the earlier refactoring in v8.4.4 via :pr:`309` that
  caused the connection manager to modify the selector map
  while looping over it -- by :user:`liamstask`.

- :issue:`312` via :pr:`316`: Added a regression test for
  the error handling in :py:meth:`~cheroot.connections.\
  ConnectionManager.get_conn` to ensure more stability
  -- by :user:`cyraxjoe`.

v8.4.4

- :issue:`304` via :pr:`309`: Refactored :py:class:`~\
  cheroot.connections.ConnectionManager` to use :py:meth:`~\
  selectors.BaseSelector.get_map` and reorganized the
  readable connection tracking -- by :user:`liamstask`.

- :issue:`304` via :pr:`309`: Fixed the server shutdown
  sequence to avoid race condition resulting in accepting
  new connections while it is being terminated
  -- by :user:`liamstask`.

v8.4.3

- :pr:`282`: Fixed a race condition happening when an HTTP
  client attempts to reuse a persistent HTTP connection after
  it's been discarded on the server in :py:class:`~cheroot.\
  server.HTTPRequest` but no TCP FIN packet has been received
  yet over the wire -- by :user:`meaksh`.

  This change populates the ``Keep-Alive`` header exposing
  the timeout value for persistent HTTP/1.1 connections which
  helps mitigate such race conditions by letting the client
  know not to reuse the connection after that time interval.

v8.4.2

- Fixed a significant performance regression introduced in
  v8.1.0 (:issue:`305` via :pr:`308`) - by :user:`mar10`.

  The issue turned out to add 0.1s delay on new incoming
  connection processing. We've lowered that delay to mitigate
  the problem short-term, better fix is yet to come.

v8.4.1

- Prevent :py:exc:`ConnectionAbortedError` traceback from being
  printed out to the terminal output during the app start-up on
  Windows when built-in TLS adapter is used (:issue:`302` via
  :pr:`306`) - by :user:`mxii-ca`.

v8.4.0

- Converted management from low-level :py:func:`~select.select` to
  high-level :py:mod:`selectors` (:issue:`249` via :pr:`301`)
  - by :user:`tommilligan`.

  This change also introduces a conditional dependency on
  ``selectors2`` as a fall-back for legacy Python interpreters.

v8.3.1

- Fixed TLS socket related unclosed resource warnings
  (:pr:`291` and :pr:`298`).
- Made terminating keep-alive connections more graceful
  (:issue:`263` via :pr:`277`).

v8.3.0

- :cp-issue:`910` via :pr:`243`: Provide TLS-related
  details via WSGI environment interface.
- :pr:`248`: Fix parsing of the ``--bind`` CLI option
  for abstract UNIX sockets.


(adam)