Bump version in nix overlay

Author: Exidex

nix/overlay.nix

@@ -5,7 +5,7 @@
 }: {
   flake.overlays.default = final: _: let
     # These must be updated following the instructions in ./nix/README.md when dependencies are updated or the version bumped
-    version = "v11";
+    version = "v12";
     npmDepsHash = "sha256-zcqn+EsxWfdxkIKUnF8kiuURtPiE6XQOaDAspuKEe64=";
     RUSTY_V8_ARCHIVE = fetchRustyV8 "130.0.2" {
       aarch64-darwin = "sha256-aWZ/4Q4Wttx37xOdBmTCPGP+eYGhr4CM1UkYq8pC7Qs=";