flake.nix: nix flake update

flake.lock

@@ -124,11 +124,11 @@
         "nixpkgs": "nixpkgs_4"
       },
       "locked": {
-        "lastModified": 1704023977,
-        "narHash": "sha256-nKf0FqdL9ONOxOK31OysC1o2I3x50dbc4gT4cMK7nzw=",
+        "lastModified": 1704189567,
+        "narHash": "sha256-TyvB15ZDGRhIqzWi5wPDXDDSOTyNbFo0RAA0yP57C24=",
         "ref": "lts/ghc-9.6.x",
-        "rev": "fe2c40f654199f4865d1d3aa19d19c39a899f6c3",
-        "revCount": 130,
+        "rev": "df4c7a644e95ea6aaa186b7555dce6a59696aa99",
+        "revCount": 132,
         "type": "git",
         "url": "https://gitlab.horizon-haskell.net/package-sets/horizon-advance"
       },