Fix incorrect fixed-derivation hash.

At least, I suppose it was incorrect.  It won't build anywhere it has not
already built.  I don't know how it built where it already built.

nixos/pkgs/zkapauthorizer-repo.nix

@@ -5,5 +5,5 @@ in
     owner = "PrivateStorageio";
     repo = "ZKAPAuthorizer";
     rev = "27a2f31e5483fa732785cf550e3beef09d67c398";
-    sha256 = "0chd3x5zvv873jah9z0dj4fpq4ika7i919dfzx53ckf395y69dzm";
+    sha256 = "10x28f1iplhskbaqxqcd68kz0llssvn261b87x1aaay3959s8ama";
   }
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