OpenAI minimal version bump.

[yaroslavyaroslav]

• I'm the package's author and/or maintainer.
• I have have read [the docs][1].
• I have tagged a release with a [semver][2] version number.
• My package repo has a description and a README describing what it's for and how to use it.
• My package doesn't add context menu entries. *
• My package doesn't add key bindings. **
• Any commands are available via the command palette.
• Preferences and keybindings (if any) are listed in the menu and the command palette, and open in split view.
• If my package is a syntax it doesn't also add a color scheme. ***
• If my package is a syntax it is named after the language it supports (without suffixes like "syntax" or "highlighting").
• I use [.gitattributes][3] to exclude files from the package: images, test files, sublime-project/workspace.

It's nothing more but a bump of a minimal version of the plugin. Actually it never was compatible with ST3 due to python 3.8 usage right from the start. So just making things right finally.

[packagecontrol-bot]

Automated testing result: SUCCESS

Packages modified:
  - OpenAI completion

[yaroslavyaroslav]

I would've ask to not rush this one. Since now it includes renaming, which I have to prepare for on the plugins side.

UPD: I decided to split these steps in sake for clarity. So this PR is a ready to go with just a minimal ST version bump.

[packagecontrol-bot]

Automated testing result: SUCCESS

Packages modified:
  - OpenAI completion