Deprecation of Python 2 and 3.4

[bbc2]

If all goes well, versions 0.18.x of python-dotenv will be the last to officially support Python 2 and Python 3.4. There won't be any guarantee in versions 0.19.0+.

Dropping support for Python 2 and 3.4 in python-dotenv will make it easier for both maintainers and contributors to add features and fix bugs. Indeed, maintaining compatibility with all versions has been a challenge and there are some issues that I'd like to solve, like #308, which will be easier once we can focus on Python 3.5+.

Versions 2 and 3.4 of Python reached the end of their life more than a year ago and pip does not support them anymore. Users of Python 2 or 3.4 will still be able to use python-dotenv 0.18.x and earlier versions.

Among our main reverse dependencies:

• Pipenv is in the process of removing support (they already removed testing with Python 2 from their CI).
• Flask requires 3.5+.
• Docker Compose requires Python 3.6+.

Let me know if you think this is going to be a problem. We can discuss it here.

[bbc2]

Version 0.19.0 was just released. It requires Python >= 3.5. See https://github.com/theskumar/python-dotenv/releases/tag/v0.19.0.