Yellowstone provider returns a `403 Forbidden` from `webapi.xanterra.net` on every request

[rhodesmusa]

Describe the bug
The Yellowstone provider returns a 403 Forbidden from webapi.xanterra.net on every request. The API was working previously (per issue #344 which shows a 200 in May 2024), so something on Xanterra's side has changed — likely a User-Agent or header check. The same URL works fine in a browser.

Failing URL:

GET https://webapi.xanterra.net/v1/api/availability/hotels/yellowstonenationalparklodges?date=2026-04-30&limit=31&rate_code=INTERNET

Original Camply Command (with --debug)

camply --debug campsites \
  --provider Yellowstone \
  --campground YLYM:RV \
  --start-date 2026-05-01 \
  --end-date 2026-06-01

Relevant debug output:

https://webapi.xanterra.net:443 "GET /v1/api/availability/hotels/yellowstonenationalparklodges?date=2026-04-30&limit=31&rate_code=INTERNET HTTP/1.1" 403 None
[WARNING] camply.providers.xanterra.yellowstone_lodging: Something went wrong with checking the Yellowstone Booking API. Will continue retrying.

(retries indefinitely, never succeeds)

Additional context

• camply version: pip3 show camply → Version: 0.34.1
• Python 3.9, macOS
• The same URL hit directly in a browser returns valid JSON availability data, confirming the endpoint is live but rejecting non-browser requests
• All 5 YNPL campgrounds are affected: YLYB:RV, YLYC:RV, YLYF:RV, YLYG:RV, YLYM:RV