ocserv: add otp support

Fixes:

ocserv[225874]: unknown option 'otp'

+2
+2
pkgs/by-name/oc/ocserv/package.nix
··· 18 18 ronn, 19 19 pam, 20 20 libxcrypt, 21 + oath-toolkit, 21 22 }: 22 23 23 24 stdenv.mkDerivation (finalAttrs: { ··· 50 51 lz4 51 52 pam 52 53 libxcrypt 54 + oath-toolkit 53 55 ]; 54 56 55 57 meta = {