Pinned GraphQL dependency (v0.13)

[kamilkisiela]

Pinning a version of GraphQL and keeping it in "dependencies" makes it impossible to use with other tools and packages, especially when trying to use different versions of graphql.

GraphQL-JS is super sensible about instanceof usage and in most cases breaks if there are multiple graphql packages installed in one repository.

Here's my attempt to use the next version of graphql-tools aws-amplify/amplify-cli#3836. E2E fails because of the problem I mentioned.

[aws-eddy]

Closing this issue as @manueliglesias's merged PR addresses this problem