libtorrent-rasterbar-{1_1_x,1_2_x}: stay with python2

pkgs/top-level/all-packages.nix

···
 
   libtorrent-rasterbar-1_2_x = callPackage ../development/libraries/libtorrent-rasterbar/1.2.nix {
     inherit (darwin.apple_sdk.frameworks) SystemConfiguration;
+    python = python2;
   };
 
-  libtorrent-rasterbar-1_1_x = callPackage ../development/libraries/libtorrent-rasterbar/1.1.nix { };
+  libtorrent-rasterbar-1_1_x = callPackage ../development/libraries/libtorrent-rasterbar/1.1.nix {
+    python = python2;
+  };
 
   libtorrent-rasterbar = libtorrent-rasterbar-2_0_x;