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/templates/frigate.container.j2

@@ -22,7 +22,9 @@ PodmanArgs=--shm-size {{ frigate_shm_size }}m
 EnvironmentFile=/etc/frigate/environ
 Volume=/var/lib/frigate/media:/media/frigate:rw,z,U
 Volume=/var/lib/frigate/tmp:/tmp:rw,z,U
+Volume=/var/lib/frigate/model_cache:/config/model_cache:rw,z,U
 Volume=/etc/frigate/config.yml:/config/config.yml:ro
+Tmpfs=/tmp/cache
 {% if frigate_enable_tpu %}
 AddDevice=/dev/apex_0
 {% endif %}
@@ -41,6 +43,7 @@ TimeoutStartSec=10m
 TimeoutStopSec=infinity
 StateDirectory=%N/tmp
 StateDirectory=%N/media
+StateDirectory=%N/model_cache
 
 [Install]
 WantedBy=multi-user.target