krdp: backport freerdp3 support to fix build

pkgs/kde/plasma/krdp/default.nix

···
   pkg-config,
   qtwayland,
   freerdp,
+  fetchpatch,
   wayland,
   wayland-protocols,
 }:
···
   patches = [
     (replaceVars ./hardcode-openssl-path.patch {
       openssl = lib.getExe openssl;
+    })
+    (fetchpatch {
+      # support for freerdp3, can be dropped with krdp 6.4
+      url = "https://invent.kde.org/plasma/krdp/-/merge_requests/69.patch";
+      hash = "sha256-5x9JUbFTw/POxBW8G/BOlo/wtcUjPU9J1V/wba1EI/o=";
     })
   ];