Drop Python 3.5 and 3.6 support

[BilousVladyslav]

There are several main reasons for this:

• According to Python release cycle, 3.5 and 3.6 versions are in end-of-life state.
• According to PyPi stats for steampy, Python 3.5 is not used at all, 3.6 almost unused.
• It would be much easier to maintain the library for newer versions of Python.

Once it's approved, I can add metadata about Python version requirements to setup.py and implement the use of f-strings (instead of % operators and str.format calls).

[BilousVladyslav]

We can even drop support for Python 3.7 as it will be officially marked as "end-of-life" in 2 months (2023-06-27).

This will allow us to use even more new Python syntax features

[jiajiaxd]

It seems that the author is no longer actively maintaining this repository. Can you upload your forked version of Steampy to PyPI? Thank you.

[woctezuma]

There was a release last month:

• https://github.com/bukson/steampy/releases/tag/0.80

and a commit to change the donation address to send bitcoins:

• 98d93cb Again change donation address

[BilousVladyslav]

Can you upload your forked version of Steampy to PyPI?

Thanks for the suggestion, but I don't really want to create another clone of this library.
With all due respect to the author, it's hard not to notice that the repository needs more attention, but I certainly wouldn't call it abandoned, that's why I create issues and PRs.
My goal is to continue the work of all contributors and improve the existing project, which is loved and used by a huge number of developers, despite its problems.

[bukson]

Thank you for your support @BilousVladyslav I am eager to mantain this library, but I am no longer into steam traded, so I will gladly review pull requests and so.

I thught that almost no one is using this library anyway, but knowing it has some community will drive my enthusiasm.

We can change support to version 3.8, but it is a breaking change so I will probably do it with version 1.0

[bukson]

After merging #278 I will make a commit with removing chat module, as it is no longer working, but I consider this a breaking change. With this change I will update minimal python to 3.8 and make version 1.0 of steampy

[bukson]

Ok so steampy now requires at lest 3.8 python