Graphql-core

Minor release with these changes:

* Consistently translate Python enums to values (198)
* Reverted the removal of the `_value` postfix (234)
* Use built-in dict as OrderedDict for Py 3.7+ (248)
* Fixed crash when sending a query with type definitions (257)
* Added py.typed file to support type checking (259)
* A newer Promise version is required (260)
* Various minor fixes

Hotfix release with one fix:

* Require rx<3 since new version is not compatible (235)

Changelog

* Fix a typo in a deprecation warning 9202021fc87db9c175e115016cd53e5d9d085ac6
* Fix collections import for Python >3.3 cdb299df3efda82a09cbb282e561c6c8aaa2efdf
* Add dict support for the default resolver 1760eaf995e2623aee4afca48ad5be0cd9098fbe
* Fix UnicodeDecodeError in format_error 87b615605ac9724c4f945e220e67b5b2d0461424
* Add extensions support to GraphQLError 3ba7f9218bca7a039b109b103cf57b1511d970c7
* Add traceback to errors from failed promises 8f736b7a6b052c07347dbd57e00bc8221af71faa
* Lots of internal clean up

Full changelog: https://github.com/graphql-python/graphql-core/compare/v2.1.0...v2.2.0

Changelog
* Improved pre-commit integration (added `black` formatter) https://github.com/graphql-python/graphql-core/commit/04560ea333ab408502d3f89574cebb0c2add1ac8
* Added `flags` config to help know when certain features are available 9059ecd0a87e0bfaf4eff53217217879672adff3
* Added official support to Python 3.7 a7ce75e339a6aaf3a0bb52175c41776edd549bdc
* Improved `GraphQLEnumType` serialization allowing python `Enum` values https://github.com/graphql-python/graphql-core/commit/0cef6fb10c41d36d9042dae968d6a1c7f2b96b51 https://github.com/graphql-python/graphql-core/commit/24687b659e3dd2713e6cd397d2179b8b4ed51163
* Improved `ExecutionResult` typing https://github.com/graphql-python/graphql-core/commit/934deca6734b40519cff13b02054848cd808601e
* Set explicit order for middleware resolvers https://github.com/graphql-python/graphql-core/commit/c27daa5d69ab54d07ac629313a1a5ef7a5d0d7b1

Release's candidates Changelog
The following list includes the changes listed in each of the release candidates for `2.1`.

Changelog
* Improved async generators 4d2f7e72bbb1f842fee4fd3178a4c1ed4e23eac6 (thanks ciscorn!)
* Added static typing with mypy fa4eeda36029680205e20059379e89189b946032 🎉
* Fixed errors in middleware when resolvers were not returning promises but Exceptions 6a3f9004362b51336e082e08b3b4a180c6a325c2

Changelog
* Fixed `quiver_cloud` backend imports 79811e108da626bff749b27dae4a35ffd1f4b2a0
* Added `to_dict` method to `ExecutionResult` ff6b490d565124f08d7b7b8d42a421ad0c185b96
* Improved middleware init speed 24be647e0cf12b0a12d858c4791f34a9bd210be3