chore(deps): update slskd/slskd docker tag to v0.21.0 (#3614)

apps/slskd/config.json

@@ -5,14 +5,15 @@
   "exposable": true,
   "id": "slskd",
   "description": "A modern client-server application for the Soulseek file-sharing network.",
-  "tipi_version": 1,
-  "version": "0.20.1",
+  "tipi_version": 2,
+  "version": "0.21.0",
   "categories": ["utilities"],
   "short_desc": "P2P downloads",
   "author": "jpdillingham",
   "source": "https://github.com/slskd/slskd",
   "supported_architectures": ["amd64", "arm64"],
-  "form_fields": [{
+  "form_fields": [
+    {
       "type": "text",
       "label": "WebUI username",
       "max": 50,

apps/slskd/docker-compose.yml

@@ -1,7 +1,7 @@
 version: "3.9"
 services:
   slskd:
-    image: slskd/slskd:0.20.1
+    image: slskd/slskd:0.21.0
     container_name: slskd
     volumes:
         - "${APP_DATA_DIR}:/app"