Graphene-federation

Chore:
Update graphql core dependency

First release officially under the [graphql-python](https://github.com/graphql-python) organization.
With this new repository, the goal is to increase exposure of this library and federate (pun intended) the maintenance effort from the community (thank you erikwrede).

Thanks to [Preply for setting up the foundations](https://medium.com/preply-engineering/apollo-federation-support-in-graphene-761a0512456d).

This release is only compatible with Graphene version > 3.0.

What's Changed
* Setup unit tests. by AndriiPidlisnyi in https://github.com/preply/graphene-federation/pull/73
* add GH actions and create a job for running unittests by sakhatskyi in https://github.com/preply/graphene-federation/pull/75
* preserve original formatting generated by schema_printer by SaulTigh in https://github.com/preply/graphene-federation/pull/68

New Contributors
* AndriiPidlisnyi made their first contribution in https://github.com/preply/graphene-federation/pull/73
* sakhatskyi made their first contribution in https://github.com/preply/graphene-federation/pull/75
* SaulTigh made their first contribution in https://github.com/preply/graphene-federation/pull/68

**Full Changelog**: https://github.com/preply/graphene-federation/compare/0.1.0...0.2.0

Implemented support of `provides` https://www.apollographql.com/docs/apollo-server/federation/federation-spec/#provides

Now the library supports full apollo federation specification :tada:

Fix issue with regexp mismatch for `external` and `requires` directive
https://github.com/preply/graphene-federation/issues/26

Fix camelCase isse: https://github.com/preply/graphene-federation/pull/19
Add `requires` directives https://github.com/preply/graphene-federation/pull/22