[BUG] Pi-hole v6 API endpoint change
**Describe the bug**
It looks like Pi-hole v6 changed their API endpoint, resulting in a breaking change for homebridge-pihole

**To Reproduce**
Steps to reproduce the behavior:
1. Upgrade Pi-hole to v6
2. Trigger a disable of Pi-hole in Homebridge using homebridge-pihole
3. Note in the Pi-hole web console that it isn't disabled
4. Note "WARNING: API: Bad request (The API is hosted at pi.hole/api, not pi.hole/admin/api)" in Pi-hole logs
