Update Gravity version to 1.0.0 pre-release

[natefoo]

This will install the latest version merged to the release_1.x branch. We'll make a proper 1.0.0 release and pin it around 23.0 branch time, but I want to get this out there and used by more people than just me before we get close to the release. Gravity 1.0.0 is a pretty huge overhaul from the 0.x version. Most notably, the configstate file is gone (hence dropping the $GRAVITY_STATE_DIR stuff). It also fully supports systemd in both system (root) and user (unprivileged) modes.

1.0.0 is fairly well tested and so problems will hopefully be minimal.

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.

[natefoo]

and so problems will hopefully be minimal

What on earth would've compelled me to make such a fate-tempting statement. =P

[natefoo]

[mvdbeek]

[github-actions]

This PR was merged without a "kind/" label, please correct.

[mvdbeek]

Thank you @natefoo and @hexylena, very cool!