parse headers in parseEvent hook

Author: sweeetland

src/hooks/parseEvent.ts

@@ -2,12 +2,22 @@ import { Hook } from '../index'
 
 export const parseEvent: Hook = async state => {
     const { event } = state
-    const { body, pathParameters, queryStringParameters, multiValueQueryStringParameters } = event
+    const {
+        body,
+        pathParameters,
+        queryStringParameters,
+        multiValueQueryStringParameters,
+        headers,
+    } = event
 
     if (typeof body === 'string') {
         event.body = JSON.parse(body)
     }
 
+    if (typeof headers === 'string') {
+        event.headers = JSON.parse(headers)
+    }
+
     if (!pathParameters) {
         event.pathParameters = {}
     }