Set go path during upgrade

src/freedombone

       echo 'git pull' >> /etc/cron.weekly/$UPGRADE_SCRIPT_NAME
       echo 'chown -R git:git /home/git' >> /etc/cron.weekly/$UPGRADE_SCRIPT_NAME
       echo 'chmod 600 /home/git/go/src/github.com/gogits/gogs/custom/conf/app.ini' >> /etc/cron.weekly/$UPGRADE_SCRIPT_NAME
+      echo 'GOPATH=/home/git/go' >> /etc/cron.weekly/$UPGRADE_SCRIPT_NAME
       echo 'go build' >> /etc/cron.weekly/$UPGRADE_SCRIPT_NAME
       echo 'systemctl restart gogs' >> /etc/cron.weekly/$UPGRADE_SCRIPT_NAME
   fi