rofi-pass: refactor add new optional dependency pass-otp

Rofi-pass as of a year ago added support for OTP passwords. This
dependency is "optional" but extremely nice to have as a default.

https://github.com/carnager/rofi-pass#requirements

pkgs/tools/security/pass/rofi-pass.nix

@@ -32,7 +32,7 @@ stdenv.mkDerivation rec {
     gnugrep
     gnused
     libnotify
-    pass
+    (pass.withExtensions (ext: [ ext.pass-otp ]))
     pwgen
     rofi
     utillinux