google-authenticator-failed-to-use-libqrencode - use libqrencode 4

pkgs/os-specific/linux/google-authenticator/default.nix

···
   buildInputs = [ pam ];
 
   preConfigure = ''
-    sed -i "s|libqrencode.so.3|${qrencode}/lib/libqrencode.so.3|" src/google-authenticator.c
+    sed -i "s|libqrencode.so.4|${qrencode}/lib/libqrencode.so.4|" src/google-authenticator.c
   '';
 
   installPhase = ''