Pysmartthings

- added support for windowShadeLevel capability
- Updated python target versions
- Updated dependencies

What's Changed
* Bump aiohttp from 3.6.2 to 3.7.4 by dependabot in https://github.com/andrewsayre/pysmartthings/pull/50
* Update dependencies and remove old CI by andrewsayre in https://github.com/andrewsayre/pysmartthings/pull/59
* Initial CI with GitHub Actions by andrewsayre in https://github.com/andrewsayre/pysmartthings/pull/60
* Add pypi package workflow by andrewsayre in https://github.com/andrewsayre/pysmartthings/pull/61

**Full Changelog**: https://github.com/andrewsayre/pysmartthings/compare/0.7.6...0.7.7

- Add additional Power Consumption attributes (47)

- Remove tests from package
- Correct `gasMeter` capability
- Update CI/CD config

- Update dependencies
- Add constants for `gasMeter`
- Update Install URL