Add photoprism-db to tipi network

apps/photoprism/docker-compose.yml

@@ -53,4 +53,6 @@ services:
       MARIADB_DATABASE: "photoprism"
       MARIADB_USER: "photoprism"
       MARIADB_PASSWORD: "photoprism"
-      MARIADB_ROOT_PASSWORD: "photoprism"
+      MARIADB_ROOT_PASSWORD: "photoprism"
+    networks:
+      - tipi_main_network