nix: intentionally downgrade rust toolchain to unblock CI for now

Author: querolita

flake.nix

@@ -103,8 +103,8 @@
           ((pkgs.rustChannelOf
             {
               channel = "nightly";
-              date = "2024-09-05";
-              sha256 = "sha256-3aoA7PuH09g8F+60uTUQhnHrb/ARDLueSOD08ZVsWe0=";
+              date = "2024-06-13";
+              sha256 = "sha256-s5nlYcYG9EuO2HK2BU3PkI928DZBKCTJ4U9bz3RX1t4=";
             }).rust.override
             {
               targets = [
@@ -205,7 +205,7 @@
             checkPhase = if pkgs.stdenv.isDarwin then "" else null;
             text =
               ''
-                if [ "$1" = run ] && { [ "$2" = nightly-2024-09-05 ] || [[ "$2" =~ 1.79-x86_64* ]]; }
+                if [ "$1" = run ] && { [ "$2" = nightly-2024-06-13 ] || [[ "$2" =~ 1.79-x86_64* ]]; }
                 then
                   echo using nix toolchain
                   ${rustup}/bin/rustup run nix "''${@:3}"