synergy: track upstream repository name change.

pkgs/applications/misc/synergy/default.nix

···
 
   src = fetchFromGitHub {
     owner = "symless";
-    repo = "synergy";
+    repo = "synergy-core";
     rev = "v${version}-stable";
     sha256 = "0ksgr9hkf09h54572p7k7b9zkfhcdb2g2d5x7ixxn028y8i3jyp3";
   };