lorri: fix useFetchCargoVendor

The script I ran to bulk migrate packages didn't account for cargoHash
being in a let, so here it just introduced an unused
useFetchCargoVendor binding rather than passing it to
buildRustPackage.

Fixes: c597750454b1 ("treewide: migrate to fetchCargoVendor, batch 2")

pkgs/tools/misc/lorri/default.nix

···
   # Also don’t forget to run `nix-build -A lorri.tests`
   version = "1.7.1";
   sha256 = "sha256-dEdKMgE4Jd8CCvtGQDZNDCYOomZAV8aR7Cmtyn8RfTo=";
-  useFetchCargoVendor = true;
-  cargoHash = "sha256-d1kXwb2WsF3J5AyD8wrrnGtCMYQ4P2mtiuJLMyCDPdM=";
+  cargoHash = "sha256-pRtc0cDVIBqbCbC1weFOhZP29rKAE1XdmM6HE5nJKRU=";
 
 in
 (rustPlatform.buildRustPackage rec {
···
     "doc"
   ];
 
+  useFetchCargoVendor = true;
   inherit cargoHash;
   doCheck = false;