setup.py: Add requires for installation from tarball

setup.py

@@ -79,6 +79,9 @@ extras_require = {
 if sys.platform == 'win32':
     requires.append('colorama>=0.3.5')
 
+if sys.version_info < (3, 5):
+    requires.append('typing')
+
 # Provide a "compile_catalog" command that also creates the translated
 # JavaScript files if Babel is available.