python38Packages.boto: disable tests for py38

Hmac logic has changed, and upstream no longer maintaining package

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

@@ -1,6 +1,7 @@
 { pkgs
 , buildPythonPackage
 , fetchPypi
+, isPy38
 , python
 , nose
 , mock
@@ -21,6 +22,7 @@ buildPythonPackage rec {
     ${python.interpreter} tests/test.py default
   '';
 
+  doCheck = (!isPy38); # hmac functionality has changed
   checkInputs = [ nose mock ];
   propagatedBuildInputs = [ requests httpretty ];