swiftpm2nix: fix prefetch regression by downgrading nix

Ref: NixOS/nix#11681

pkgs/development/compilers/swift/swiftpm2nix/default.nix

@@ -1,5 +1,17 @@
-{ lib, stdenv, callPackage, makeWrapper, jq, nix-prefetch-git }:
+{
+  lib,
+  stdenv,
+  callPackage,
+  makeWrapper,
+  jq,
+  nix-prefetch-git,
+  nixVersions,
+}:
 
+let
+  # https://github.com/NixOS/nix/issues/11681
+  nix-prefetch-git' = nix-prefetch-git.override { nix = nixVersions.nix_2_19; };
+in
 stdenv.mkDerivation {
   name = "swiftpm2nix";
 
@@ -10,7 +22,12 @@ stdenv.mkDerivation {
   installPhase = ''
     install -vD ${./swiftpm2nix.sh} $out/bin/swiftpm2nix
     wrapProgram $out/bin/$name \
-      --prefix PATH : ${lib.makeBinPath [ jq nix-prefetch-git ]} \
+      --prefix PATH : ${
+        lib.makeBinPath [
+          jq
+          nix-prefetch-git'
+        ]
+      } \
   '';
 
   preferLocalBuild = true;