chore(deps): update ghcr.io/open-webui/open-webui docker tag to v0.8.0

library/compose/openwebui/compose.yaml.j2

@@ -1,6 +1,6 @@
 services:
   {{ service_name }}:
-    image: ghcr.io/open-webui/open-webui:0.7.2
+    image: ghcr.io/open-webui/open-webui:v0.8.0
     container_name: {{ container_name }}
     {#
       Set container hostname for identification