🧹 Remove compatibility code: Python < 3.6

[abn]

This is a great issue to work on if you are new to the Poetry code base and want to start contributing. Over the years the poetry code base has added various fixes that catered to now unsupported versions of python. With the release of 1.2, we will drop support for all Python versions prior to 3.6. With this we want to clean up the code base of any such workarounds we did to support backwards compatibility and/or quirks.

We would like to invite first time contributors to work on helping us remove these bits of code that we no longer require. Small changes are welcome.

If you are submitting a pull request associated with this, please keep the pull requests small and modular. This means, do not do too much in one PR and try to do only closely related changes in on PR. Additionally, make sure you add this to your PR description.

Relates-to: #3860

If this is your first contribution here, please refer to #3061 before continuing.

[abn]

This should now be done thanks largely to the pyugrade plugin.