nix: remove spurious flake 'follow' directive

Apparently this isn't needed anymore.

Signed-off-by: Austin Seipp <[email protected]>

flake.nix

@@ -8,7 +8,6 @@
     # For installing non-standard rustc versions
     rust-overlay.url = "github:oxalica/rust-overlay";
     rust-overlay.inputs.nixpkgs.follows = "nixpkgs";
-    rust-overlay.inputs.flake-utils.follows = "flake-utils";
   };
 
   outputs = { self, nixpkgs, flake-utils, rust-overlay }: {