update zen browser to 1.19.2b (#11)

automated update of zen browser appimage version and hash

## changelog
from `1.19.2a` to `1.19.2b`

upstream release: https://github.com/zen-browser/desktop/releases/tag/1.19.2b

# Zen Stable Release

## Security

[Various security fixes](https://www.mozilla.org/en-US/security/advisories/mfsa2026-19/)

## New Features

- Updated to Firefox 148.0.2

## Fixes

- Fixed some RSS live folders not working with certain feeds. ([#12685](https://github.com/zen-browser/desktop/issues/12685))

- Improved performance for spaces, specially when switching between them. ([#11851](https://github.com/zen-browser/desktop/issues/11851))

- Other minor bug fixes and improvements.

Co-authored-by: gitea actions <actions@localhost>
Reviewed-on: https://gitea.unrail.xyz/thomas/nixos-config/pulls/11

modules/pkgs/zen-browser.nix

@@ -1,7 +1,7 @@
 {lib, ...}: {
   perSystem = {pkgs, ...}: let
     pname = "zen-browser";
-    version = "1.19.2a";
+    version = "1.19.2b";
 
     src = pkgs.fetchurl {
       url = "https://github.com/zen-browser/desktop/releases/download/${version}/zen-x86_64.AppImage";