Graphql-core

Public release of GraphQL-core-next, based on [GraphQL.js v14.1.1](https://github.com/graphql/graphql-js/releases/tag/v14.1.1).

In addition to incorporating the latest changes from GraphQL.js,
this release also contains the following improvements and changes:

* Add traceback to GraphQLErrors (23)
* Fix lexer issue with empty string (18)
* Keep a list of middleware resolvers (16)
* Support `__typename` attribute on data objects
* Restrict output via inspect() in error messages
* Remove `contain_subset` helper since it is not used any more

Public release of GraphQL-core-next, based on [GraphQL.js v14.0.2](https://github.com/graphql/graphql-js/releases/tag/v14.0.2).

Besides incorporating the latest changes from GraphQL.js,
this release also contains the following improvements and changes:

* Support GraphQL middleware (7)
* Support custom ExecutionContext (6)
* Await resolvers in parallel (11)
* Await subscribed execution results (10)
* Use inspect() instead of repr() in error messages (12)
* Code formatting with "black" (8)

Final version of the first public release of GraphQL-core-next, based on [GraphQL.js v14.0.0](https://github.com/graphql/graphql-js/releases/tag/v14.0.0).

Second release candidate for GraphQL-core-next, based on [GraphQL.js v14.0.0-rc.2](https://github.com/graphql/graphql-js/releases/tag/v14.0.0-rc.2).

Changelog
- Add right stacktrace to `Exception` https://github.com/graphql-python/graphql-core/commit/1de69e5d2b95f17487b839bb97cac5d3e5465c06
- Use `promise.get()` instead of `promise.value` https://github.com/graphql-python/graphql-core/commit/11f0513d8f68f3889bd37268efb2e4927028bb61
- Added `loop` option in `AsyncioExecutor` https://github.com/graphql-python/graphql-core/commit/3258d297a877d0215764a28f281698b8bdd6b6b2

Changelog
- Improve validation error message when field names conflict https://github.com/graphql-python/graphql-core/commit/3caa3e0efffcf99b4f8f8f58a82a4b62ea918e71