connman: remove unneeded deps from nativeBuildInputs

pkgs/tools/networking/connman/connman.nix

···
     pkgconfig
     file
   ]
-    ++ optionals (enableOpenvpn) [ openvpn ]
-    ++ optionals (enableOpenconnect) [ openconnect ]
-    ++ optionals (enableVpnc) [ vpnc ]
     ++ optionals (enablePolkit) [ polkit ]
     ++ optionals (enablePptp) [ pptp ppp ]
     ++ optionals (firewallType == "iptables") [ iptables ]