fixing travis yaml

Author: zookzook

.travis.yml

@@ -7,18 +7,16 @@ otp_release: 22.0
 addons:
   apt:
     packages:
+      - python3
       - python3-pip
 
-before_install:
-  - sudo apt-get update
-  - sudo apt-get install python3
-
 install:
   - wget https://fastdl.mongodb.org/linux/mongodb-linux-x86_64-ubuntu1604-4.4.0-rc0.tgz
   - mkdir ${PWD}/mongodb
   - tar xzf mongodb-linux-x86_64-ubuntu1604-4.4.0-rc0.tgz --strip-components=1 -C ${PWD}/mongodb
 
 before_script:
+  - pyenv global 3.6
   - pip3 install --upgrade pip
   - pip3 install mtools[all]
   - export PATH=${PWD}/mongodb/bin/:$PATH