Update inputs.nixpkgs

[dsalaza4]

Makes currently uses a pretty old version of nixpkgs to build its container:

makes/makes.nix

Lines 138 to 141 in 1311f28

	nixpkgs = fetchNixpkgs {
	rev = "f88fc7a04249cf230377dd11e04bf125d45e9abe";
	sha256 = "1dkwcsgwyi76s1dqbrxll83a232h9ljwn4cps88w9fam68rf8qv3";
	};

Let's:

1. Update inputs.nixpkgs to a more recent version
2. Make sure the container is building properly
3. Prefer using __nixpkgs__ for building the container