Update changelog to include version 0.7.0
# CHANGELOG
+## 0.7.0 (UNRELEASED)
+
+- Added support for custom schema directives.
+- Added support for synchronous extensions and synchronous versions of `ApolloTracing` and `OpenTracing` extensions.
+- Added `context` argument to `has_errors` and `format` hooks.
+
+
## 0.6.0 (2019-08-12)
- Updated `graphql-core-next` to 1.1.1 which has feature parity with GraphQL.js 14.4.0.
