pocket-casts: Bump electron version to 42

Upstream already pinned Electron to 42 in their `package.json` for
v0.13.0.

(cherry picked from commit 8bb07fcc0f)

pkgs/by-name/po/pocket-casts/package.nix

@@ -5,10 +5,10 @@
   makeDesktopItem,
   copyDesktopItems,
   makeWrapper,
-  electron_40,
+  electron_42,
 }:
 let
-  electron = electron_40;
+  electron = electron_42;
 in
 buildNpmPackage rec {
   pname = "pocket-casts";