Do not add to cache if the value is greater than 25MB

[jackzh22]

• If the value to store in cache is greater than 25MB (Cloudflare's KV limit for the value) an error would be thrown from thecache.put call ({"error":"KV PUT failed: 413 Value length of 26960532 exceeds limit of 26214400."}, which would cause a 500 Internal Server Error thrown from the get/getAll calls.