r/frigate: Update to v0.15

Frigate has evolved a lot over the past year or so since v0.13.
Notably, some of the configuration options have been renamed, and
_events_ have become _alerts_ and _detections_.  There's also now
support for authenication, though we don't need it because we're using
Authelia.

roles/frigate/defaults/main.yml

@@ -1,4 +1,4 @@
-frigate_image_tag: 0.12.1
+frigate_image_tag: 0.15.1
 frigate_image: ghcr.io/blakeblackshear/frigate:{{ frigate_image_tag }}
 frigate_mqtt:
   host: localhost
@@ -10,6 +10,8 @@ frigate_enable_gpu: false
 frigate_enable_tpu: false
 frigate_shm_size: 256
 frigate_config:
+  database:
+    path: /media/frigate/frigate.db
   mqtt: '{{ frigate_mqtt }}'
   detectors: '{{ frigate_detectors }}'
   cameras: '{{ frigate_cameras }}'