- list(filter(lambda x: x != "", sys.path))
+ [p for p in sys.path if p != ""]

Change missing provider plugins from errors to warnings for python and
perl. Also give proper advice under the ADVICE section instead of just
the errors.

These versions of python has reached End-of-life. getting rid
of python2 support removes a lot of logic to support two
incompatible python versions in the same version.

"3.10" < "3.3" but v3.10 > v3.3
Fixes #14586

Certain values of 'wildignore', .e.g `*/node_modules/**`, would make the
provider checks not find the right executables.

Fixes https://github.com/neovim/neovim/issues/14388

Python 3.9 was released, so we need to add support for the upcoming Python 3.10.
Python 3.5 and earlier reached their end-of-life.

PEP 478: Python 3.5  Release Schedule: https://www.python.org/dev/peps/pep-0478
PEP 596: Python 3.9  Release Schedule: https://www.python.org/dev/peps/pep-0596
PEP 619: Python 3.10 Release Schedule: https://www.python.org/dev/peps/pep-0619

When UV_OVERLAPPED_PIPE was used for the pipe passed to the child process, a
problem occurred with the standard input of the .Net Framework application
(#11809). Therefore, add the overlapped option to jobstart() and change it so
that it is set only when necessary

3.9's scheduled for beta release today.
https://www.python.org/dev/peps/pep-0596/

Python 3.8 was released 2019-10-14:

  https://www.python.org/dev/peps/pep-0569

sys.path.remove("") raises ValueError if the item is missing.

https://docs.python.org/3/library/functions.html#filter:
> filter(function, iterable) is equivalent to the generator expression (item
> for item in iterable if function(item))

fixes #11293