chore: let direnv watch every .nix file when using nix

Author: kukovecz

.envrc

@@ -3,7 +3,7 @@
 source_env_if_exists .envrc.user
 
 if ${UNBLOB_USE_DEVENV:-true}; then
-    watch_file flake.nix flake.lock devenv.nix
+    watch_file *.nix flake.lock
     use nix \
         --option extra-substituters "https://unblob.cachix.org" \
         --option extra-trusted-public-keys "unblob.cachix.org-1:5kWA6DwOg176rSqU8TOTBXWxsDB4LoCMfGfTgL5qCAE="