update pb submodule rev

Author: manveru

nix/overlay.nix

@@ -20,7 +20,7 @@ inputs: final: prev: {
   # ourselves instead.
   mantis-extvm-pb = builtins.fetchGit {
     url = "https://github.com/input-output-hk/mantis-extvm-pb";
-    rev = "6b3039be92882df6ef6c15887c8d0b5f10c86d6f";
+    rev = "53eb31f3c59f7200994915b834e626bd292df7ed";
   };
 
   mantisPkgs = final.callPackage ./pkgs/mantis { src = ../.; };