switch from alejandra -> nixpkgs-fmt

alejandra has someone questionable choices for formatting that no one would apply to there code if they would format manually.
nixpkgs-fmt seems to produce more readable results.

flake-parts/pre-commit.nix

@@ -1,4 +1,4 @@
-{self, ...}: {
+{ self, ... }: {
   pre-commit.settings.hooks.alejandra.enable = true;
   pre-commit.settings.hooks.shellcheck.enable = true;
 }