Revert "nix: 2.3.10 -> 2.3.11"

This reverts commit 6f6b2cdc98.

Version wasn't updated, and apparently a patch didn't apply.  Let's do
this upgrade properly, in a PR, but for now I'm reverting so we don't
have a broken nix package in master.

nixos/modules/installer/tools/nix-fallback-paths.nix

@@ -1,6 +1,6 @@
 {
-  x86_64-linux = "/nix/store/d1ppfhjhdwcsb4npfzyifv5z8i00fzsk-nix-2.3.11";
-  i686-linux = "/nix/store/c6ikndcrzwpfn2sb5b9xb1f17p9b8iga-nix-2.3.11";
-  aarch64-linux = "/nix/store/fb0lfrn0m8s197d264jzd64vhz9c8zbx-nix-2.3.11";
-  x86_64-darwin = "/nix/store/qvb86ffv08q3r66qbd6nqifz425lyyhf-nix-2.3.11";
+  x86_64-linux = "/nix/store/iwfs2bfcy7lqwhri94p2i6jc87ih55zk-nix-2.3.10";
+  i686-linux = "/nix/store/a3ccfvy9i5n418d5v0bir330kbcz3vj8-nix-2.3.10";
+  aarch64-linux = "/nix/store/bh5g6cv7bv35iz853d3xv2sphn51ybmb-nix-2.3.10";
+  x86_64-darwin = "/nix/store/8c98r6zlwn2d40qm7jnnrr2rdlqviszr-nix-2.3.10";
 }

pkgs/tools/package-management/nix/default.nix

@@ -199,7 +199,7 @@ in rec {
     version = "2.3.10";
     src = fetchurl {
       url = "https://nixos.org/releases/nix/${pname}-${version}/${pname}-${version}.tar.xz";
-      sha256 = "89a8d7995305a78b1561e6670bbf1879c791fc4904eb094bc4f180775a61c128";
+      sha256 = "a8a85e55de43d017abbf13036edfb58674ca136691582f17080c1cd12787b7ab";
     };
 
     patches = [(