Use newer OSX image.

vaibhavpandeyvpz · web-flow · commit 2d94810719f8 · 2020-04-14T11:14:00.000+05:30
diff --git a/.travis.yml b/.travis.yml
@@ -10,7 +10,7 @@ matrix:
           packages:
             - libgl1-mesa-dev
     - os: osx
-      osx_image: xcode9
+      osx_image: xcode9.3
 
 before_install: |
   if [[ $TRAVIS_OS_NAME == "linux" ]]; then
