Enlighten

**Bug Fixes**
- Fix time assumption in tests 74

**Changes**
- [englighten.format_time()](https://python-enlighten.readthedocs.io/en/stable/api.html#enlighten.format_time) is now public
- Formerly undocumented and only available in ``enlighten._util``
- ``elapsed`` field for status bars now stops accumulating when the bar is closed (66)
- Add [FAQ entry](https://python-enlighten.readthedocs.io/en/stable/faq.html#why-does-the-output-get-scrambled-when-the-number-of-progress-bars-exceeds-the-terminal-height) to document limitation of progress bars to terminal height. (68)
- Reduce instances of subcounters jumping forward and backward (69)

**Housekeeping**
- Removed use of ``time.time()`` and ``time.sleep()`` from tests
- Improved speed and stability when running in parallel
- Various updates to CI configuration

**Bug Fixes**
- Resize handler crashes when window height is reduced and manager has no counters 64

**Changes**
- Resize handler now does line feeds when height is increased when not threaded
- Previously only did when threaded
- A warning is raised when closing a previously closed counter
- Previously raised a non-specific error in some conditions
- If the counter would normally be refreshed before closing, it will only refresh if still attached to manager, i.e. ``leave=True``

**Housekeeping**
- Pin Pip version in Tox to support older Python versions

**Housekeeping**
- Fix API links in Read The Docs

**Housekeeping**
- Add readthedocs.yaml
- [New requirement](https://blog.readthedocs.com/migrate-configuration-v2/)

**Bug Fixes**
- Minor doc fixes
- Improved context manager example
- Remove unexpected reference to enlighten.counter in example
- Thanks to raffaem for reporting 63

**Changes**
- Improved colors in multiprocessing example
- Added error handling to multiprocessing example