Hey John!
I see a couple of problems in your code.
Authentication
Our API uses token-based auth, which is slightly different from Basic auth. Looks like you’re using both in your code… 
I’d suggest removing that third header (Basic + encodedData) because Basic not needed to access our API.
Request Format and Verb
All requests to our API should be POST requests, with a “query” parameter sent in the body. Check out this article for a quick introduction: https://support.monday.com/hc/en-us/articles/360005144659-Does-monday-com-have-an-API-?abcb=8536
Let me know if that helps!