pdfium-binaries: add python3Packages.pypdfium2 to passthru.tests

This is to make sure pypdfium2 build is not broken on version update.

Signed-off-by: Ihar Hrachyshka <ihar.hrachyshka@gmail.com>

pkgs/by-name/pd/pdfium-binaries/package.nix

@@ -2,6 +2,7 @@
   lib,
   fetchzip,
   stdenv,
+  python3Packages,
 }:
 let
   version = "6968";
@@ -41,7 +42,12 @@ stdenv.mkDerivation {
     runHook postInstall
   '';
 
-  passthru.updateScript = ./update.sh;
+  passthru = {
+    updateScript = ./update.sh;
+    tests = {
+      inherit (python3Packages) pypdfium2;
+    };
+  };
 
   meta = {
     description = "Binary distribution of PDFium";