fix: only run CI when the nix stuff changes

Author: hbjydev

.github/workflows/cache.yaml

@@ -4,8 +4,10 @@ on:
   push:
     branches:
       - main
-    paths-ignore:
-      - .gitignore
+    paths:
+      - config/**
+      - flake.nix
+      - flake.lock
 
 jobs:
   cache: