[UPD] Remove exposed Key, Add version Param, Deprecated support for python 2

[mashanz]

This PR will fix view issue here:

1. There a lot exposed Key that may be abused
2. Add version param so the user can call midtransclient.__version__ to check this modul version for better version control & integration or backward compatibility.
3. Remove python 2 support and add python 3.10

[rizdaprasetya]

Thanks for the quick PR! Mostly looks good, we'll be reviewing this in-depth sometimes on next weekday. Some quick comments:

There a lot exposed Key that may be abused

It is actually intentional for the keys to be hardcoded, so that:

• example flask app can be easily run without requiring people to sign up first, it is good for demonstration purpose.
• test result can be consistent and centralized to one test account
  So it is fine to leave the keys exposed. We acknowledge & are ok with the risk. It is also just a sandbox env key with no major potential harm (which anyway we can block anytime from our side if we need to).

We'll be back soon to further review & merge, thanks!

[mashanz]

I see, I thought it is a mistakes, There are no explanation why the key are there to begin with.
Thanks for the comments and explanation.

[rizdaprasetya]

Overall the PR looks good 👍 thanks! I reverted the API keys removal, fixed test, and added some notes to improve this PR. Should be good now.

We'll merge this now (but not release it yet, we'll release together with that 1 other PR about Python 2 compatibility). Thanks for your contribution @mashanz ! Appreciate your solid works! 😃

[mashanz]

Thanks @rizdaprasetya 🔥🎉👍🏻