build: also installing python3 version of kwant
build: also installing python3 version of kwant

DrXyzzy/smc,sagemathinc/smc,DrXyzzy/smc,DrXyzzy/smc,tscholl2/smc,tscholl2/smc,sagemathinc/smc,tscholl2/smc,DrXyzzy/smc,tscholl2/smc,sagemathinc/smc,sagemathinc/smc,tscholl2/smc