Cannot load Elastic API file with available versions

Hi, and thanks so much for this time-saver module!

I have a setup in which I use `graphql-compose-elasticsearch` within an AWS Lambda handler.

When I run it locally with the serverless framework, all works well, but when I deploy the function, I start to get error messages.

The first one was about a wrong parameter passed to the function creating the search() resolver. It was strange, because I used 1:1 the examples from the documentation.

When I deployed a non-minified version of the code, howerver, I received another error:

```json
{
"errorMessage":"Cannot load Elastic API file with avaliable versions from /node_modules/elasticsearch/src/lib/apis/index.js",
"errorType":"Error",
"stackTrace":[
"Function.loadApiListFile (/var/task/src/api/graphql.js:164571:13)",
"Function.findApiVersionFile (/var/task/src/api/graphql.js:164581:42)",
"new ElasticApiParser (/var/task/src/api/graphql.js:164541:121)",
"createSearchResolver (/var/task/src/api/graphql.js:170075:18)",
"composeWithElastic (/var/task/src/api/graphql.js:165022:84)",
"createHandler (/var/task/src/api/graphql.js:262504:111)",
""
]
}
```

I feel I'm getting closer to the problem, because I found #6 where there was a discussion about getting the versions from the Elasticsearch client, rather than the file system.

In a lambda function, I can't rely on the file system or globals (like in containers), because the contained environment the functions live should be stateless.

Is there a specific reason the fix in #6 didn't use the suggestion?

```js
const es = require('elasticsearch');
console.log(es.Client.apis);
```

Maybe the information format which is expected is different?