[ci] bump yarn version to 1.6.0

Signed-off-by: Alex Tugarev <[email protected]>

.travis.yml

@@ -64,7 +64,7 @@ before_script:
   - export DISPLAY=:99.0; sh -e /etc/init.d/xvfb start ;
   - google-chrome-stable --headless --disable-gpu --remote-debugging-port=9222 http://localhost \&  ;
 before_install:
-  - curl -o- -L https://yarnpkg.com/install.sh | bash -s -- --version 1.2.1
+  - curl -o- -L https://yarnpkg.com/install.sh | bash -s -- --version 1.6.0
   - export PATH=$HOME/.yarn/bin:$PATH ;
 install: yarn
 script: travis_retry yarn test ;

appveyor.yml

@@ -13,6 +13,7 @@ branches:
 
 install:
   - ps: Install-Product node $env:nodejs_version $env:platform
+  - npm install [email protected] -g
   - netsh advfirewall firewall add rule name="SeleniumIn" dir=in action=allow protocol=TCP localport=4444
   - netsh advfirewall firewall add rule name="SeleniumOut" dir=out action=allow protocol=TCP localport=4444