frappix: bump to 474adcf, drop insights mysqlclient override

Upstream now ships mysqlclient with insights (kurogeek/frappix 474adcf).

flake.lock

@@ -464,11 +464,11 @@
         "std": "std"
       },
       "locked": {
-        "lastModified": 1789106589,
-        "narHash": "sha256-RMQdAvDaa4eUcdePDqUGAhnyTtzKxc6a8abauy8bzb0=",
+        "lastModified": 1793940934,
+        "narHash": "sha256-upFVzpfpKUqk52/daFyoRaFmJ5kQ3k3X4a4AY9fHrjU=",
         "owner": "kurogeek",
         "repo": "frappix",
-        "rev": "dbfa76d84df6354bd7528c9d0c407387f66c3e33",
+        "rev": "474adcf78b4438bc68f300be8b5732be638694e1",
         "type": "github"
       },
       "original": {