SUP-6396: Pin version of urllib3

[skalish]

↪️ Pull Request

This PR pins the version of the transitive dependency urllib3 (required by requests) to use versions before 2.0.0.

It also updates the tested versions of Python and upgrades some dev dependencies.

✔️ PR Todo

• [x] Update relevant docs + docstrings

[github-actions[bot]]

:tada: This PR is included in version 1.7.0 :tada:

The release is available on:

• v1.7.0
• GitHub release

Your semantic-release bot :package::rocket: