test: auto sync chromedriver / chrome versions (#501)

Author: josh

.travis.yml

@@ -42,7 +42,9 @@ matrix:
         - pyenv global system
         - python -m pip install codecov
         - pip freeze
-        - wget -N "https://chromedriver.storage.googleapis.com/$(curl https://chromedriver.storage.googleapis.com/LATEST_RELEASE_75)/chromedriver_linux64.zip" -P ~/
+        - |
+          CHROME_MAJOR_VERSION="$(dpkg -s google-chrome-stable | sed -nr 's/Version: ([0-9]+).*/\1/p')"
+          wget -N "https://chromedriver.storage.googleapis.com/$(curl https://chromedriver.storage.googleapis.com/LATEST_RELEASE_${CHROME_MAJOR_VERSION})/chromedriver_linux64.zip" -P ~/
         - unzip ~/chromedriver_linux64.zip -d ~/
         - rm ~/chromedriver_linux64.zip
         - sudo install -m755 ~/chromedriver /usr/local/bin/