Gem Release 6.1.0 Passing Post Body Results in Error

[kjanoudi]

Issue Summary

When running version 6.1.0, and executing a call to a properly formatted request to the client.contactdb.recipients.post method, the resulting error is undefined method bytesize' for #Array:0x00007f11061d84e0`

Steps to Reproduce

1. Use gem version 6.1.0 (6.0.4 does not have this issue)
2. Follow code steps here: https://github.com/sendgrid/sendgrid-ruby/blob/master/USAGE.md#post-contactdbrecipients
3. See resulting error: undefined method bytesize' for #Array:0x00007f11061d84e0`

Exception/Log

Technical details:

• sendgrid-ruby version: 6.1.0
• ruby version: 2.6.5

[childish-sambino]

Able to recreate this locally. Looks related to this change: #95

This issue has been added to our internal backlog to be prioritized. Pull requests and +1s on the issue summary will help it move up the backlog.