Fix setup.py: install gevent from scratch for Python 3
Fix setup.py: install gevent from scratch for Python 3

lyudmildrx/lymph,Drahflow/lymph,itakouna/lymph,itakouna/lymph,mouadino/lymph,mamachanko/lymph,lyudmildrx/lymph,mouadino/lymph,dushyant88/lymph,torte/lymph,lyudmildrx/lymph,mouadino/lymph,alazaro/lymph,alazaro/lymph,alazaro/lymph,mamachanko/lymph,mamachanko/lymph,emulbreh/lymph,itakouna/lymph,emulbreh/lymph,deliveryhero/lymph,kstrempel/lymph,vpikulik/lymph