It's pyserial not serial

Author: me-no-dev

.travis.yml

@@ -10,7 +10,7 @@ os:
 script:
  #- set -e
  - echo -e "travis_fold:start:sketch_test_env_prepare"
- - pip install serial
+ - pip install pyserial
  - wget -O arduino.tar.xz https://www.arduino.cc/download.php?f=/arduino-nightly-linux64.tar.xz
  - tar xf arduino.tar.xz
  - mv arduino-nightly $HOME/arduino_ide