qtpass: Fix /usr/lib hardcode to pass-otp.
qtpass: Fix /usr/lib hardcode to pass-otp.

Before, the checkbox for OTP functionality could not be enabled on
NixOS, even when `(pass.withExtensions (exts: [ exts.pass-otp ]))`
was installed correctly.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs