python37Packages.JPype1: fix build

pkgs/development/python-modules/JPype1/default.nix

@@ -2,6 +2,8 @@
 , buildPythonPackage
 , fetchPypi
 , isPy27
+, pythonOlder
+, typing-extensions
 , pytest
 }:
 
@@ -15,6 +17,10 @@ buildPythonPackage rec {
     sha256 = "c6e36de9f7ef826ff27f6d5260acc710ebc585a534c12cbac905db088ab1d992";
   };
 
+  propagatedBuildInputs = lib.optionals (pythonOlder "3.8") [
+    typing-extensions
+  ];
+
   checkInputs = [
     pytest
   ];