anki: 2.1.6-beta1 -> 2.1.6-beta2, fix python 3.7

With recent switch to python 3.7 this was no longer building.

Upstream PR with the same patch: https://github.com/dae/anki/pull/266

pkgs/games/anki/default.nix

@@ -25,7 +25,7 @@
 }:
 
 buildPythonApplication rec {
-    version = "2.1.6-beta1";
+    version = "2.1.6-beta2";
     name = "anki-${version}";
 
     src = fetchurl {
@@ -35,7 +35,7 @@ buildPythonApplication rec {
         # "http://ankisrs.net/download/mirror/${name}.tgz"
         # "http://ankisrs.net/download/mirror/archive/${name}.tgz"
       ];
-      sha256 = "0yqn8qjx9dyf754jljhyyrk8mahii188nz0yifl1lr3py9sxzbsf";
+      sha256 = "0h71s1j1269x0b8481z8xf019caqglcjs32xlpzk72087ps169fa";
     };
 
     propagatedBuildInputs = [ pyqt5 sqlalchemy
@@ -53,6 +53,7 @@ buildPythonApplication rec {
     patches = [
       # Disable updated version check.
       ./no-version-check.patch
+      ./python-3.7-compat.patch
     ];
 
     buildPhase = ''