When installing Poetry through `install-poetry.py`, if `pip` is not
available, Exception should not be raised, rather installation should
be aborted with user-friendly error msg.

Fixes #4521

Co-authored-by: TurtleNishant <nishant@turtlelectric.com>
Co-authored-by: Bjorn Neergaard <bjorn@neersighted.com>

This change removes `__future__` imports and 'coding: utf-8' 
declarations.

Co-authored-by: Jason Racine <jason.racine@uplight.com>

This change adds dependabot configuration with updates disabled to
allow for restriction of manifest file selection used by the
dependency graph.

Ref: https://docs.github.com/en/code-security/supply-chain-security/keeping-your-dependencies-updated-automatically/configuration-options-for-dependency-updates

Ref: https://www.python.org/dev/peps/pep-0314/#keywords-optional 

Resovles: #4183

Related-to: #4142

HTTPretty handling of thread exception is incomplete, causing issues
for test runs. This change works around the issue by ignoring the
relevant warnings.

Pytest issues a warning as it attempts to collect `TestApplication`.
This change renames the class to `PoetryTestApplication`.

Upstream issue with pip 21.1.1 was resolved in 21.1.2. This version of
pip was embedded in virtualenv versions 20.4.7 and above.

Relates-to: python-poetry#4042

This change ensures that when complete packages are created dependency
inherits subdirectory from package if supported.

This change ensures that when complete packages are created dependency
inherits source and resolved refs from package.

This change ensures that the tests support upcoming (>1.1.0a6) changes
dropping default branch assumptions for vcs dependencies.

This change ensures that python_version comparison uses parsed versions
and does not fail with changes in pretty output.

This change ensures that generated scripts for editable package 
installs exit using return value from callable used.

When running `python` within the various shells made available on 
Windows by MSys2, `sysconfig.get_platform()` returns:

* MSys2         : `msys-3.2.0-x86-64`
* MinGW x32     : `mingw_i686`
* MinGW x64     : `mingw_x86_64`
* MinGW UCRT64  : `mingw_x86_64_ucrt`
* MinGW Clang64 : `mingw_x86_64_clang`

In the case that `sysconfig.get_platform()` *does* return `mingw` (with
no suffix), this change should still work as expected.

Related-to: #3713

This commit fixes typographical errors in the CHANGELOG, docs folder,
poetry package, and the tests. This was done via the codespell utility,
which can be found at https://github.com/codespell-project/codespell

Following a regression in #4443

* Add required_by list to pip show <package> command

* Update poetry show pendulum documentation

* Handle package name discrepancies

* Lets not force typing then

* issue-1906 Add the test back after rebase

* issue-1906 Ignore trailing spaces in the tests

Fix the detection of the system environment with custom installer

Co-authored-by: finswimmer <2164565+finswimmer@users.noreply.github.com>