Swallows GraphQL errors

If your GraphQL endpoint returns an error, this module will swallow it here: https://github.com/kevva/graphql-got/blob/v0.1.1/index.js#L38

Instead of dropping `res.body.errors`, they should be assigned to `res` (maybe as `res.errors`?). Would you accept a PR that introduces this change?

Start at index.js line 38, where the GraphQL response currently drops res.body.errors, and trace the surrounding response handling. The work is done when those errors remain available on the returned response and the repository’s existing tests confirm the behavior.

Written by the indexing model from the issue text.