Optimize implementation of TimeDelta#_serialize
Optimize implementation of TimeDelta#_serialize

marshmallow-code/marshmallow,dwieeb/marshmallow,Bachmann1234/marshmallow,daniloakamine/marshmallow,xLegoz/marshmallow,maximkulkin/marshmallow,etataurov/marshmallow,mwstobo/marshmallow,VladimirPal/marshmallow,quxiaolong1504/marshmallow,Tim-Erwin/marshmallow,bartaelterman/marshmallow