travis: upgrade before test.
travis: upgrade before test.

lzedl/PyMySQL,nju520/PyMySQL,eibanez/PyMySQL,PyMySQL/PyMySQL,jheld/PyMySQL,xjzhou/PyMySQL,boneyao/PyMySQL,pulsar314/Tornado-MySQL,mosquito/Tornado-MySQL,modulexcite/PyMySQL,NunoEdgarGub1/PyMySQL,wraziens/PyMySQL,Ting-y/PyMySQL,lzedl/PyMySQL,MartinThoma/PyMySQL,methane/PyMySQL,PyMySQL/Tornado-MySQL,jwjohns/PyMySQL,pymysql/pymysql,anson-tang/PyMySQL,yeyinzhu3211/PyMySQL,wraziens/PyMySQL,yeyinzhu3211/PyMySQL,eibanez/PyMySQL,DashaChuk/PyMySQL,xjzhou/PyMySQL,Geoion/Tornado-MySQL,aio-libs/aiomysql