Fix: APIGW v2 Request Cookie Header

[araki-yzrh]

Fixed an issue.
API Gateway v2 event "cookies" was not included in "scope.headers"

see also: https://docs.aws.amazon.com/apigateway/latest/developerguide/http-api-develop-integrations-lambda.html

v1 event

was worked.

event == {
  "version": "1.0",
  "headers": {
    "accept-encoding": "gzip, deflate",
    "cookie": "cookie1; cookie2"
  },
  ...

scope == {
  ...
  "headers": [
    [b"accept-encoding", b"gzip, deflate"],
    [b"cookie", b"cookie1; cookie2"],
  ...

v2 event

was not worked.

event == {
  "version": "2.0",
  "cookies": [
    "cookie1",
    "cookie2"
  ],
  "headers": {
    "accept-encoding": "gzip, deflate"
  },
  ...

scope == {
  ...
  "headers": [
    [b"accept-encoding", b"gzip, deflate"],
  ...

[jordaneremieff]

Great work! Thank you.