chore: remove unused dependencies

Remove 30 dependencies across 18 packages that have no imports in
source code and are not peer dependencies of any other dependency.

Signed-off-by: Fredrik Adelöw <freben@spotify.com>
Made-with: Cursor

plugins/app-backend/package.json

@@ -68,8 +68,7 @@
     "helmet": "^6.0.0",
     "knex": "^3.0.0",
     "lodash": "^4.17.21",
-    "luxon": "^3.0.0",
-    "yn": "^4.0.0"
+    "luxon": "^3.0.0"
   },
   "devDependencies": {
     "@backstage/backend-app-api": "workspace:^",