Travis: Use Homebrew addon to improve performance

diff --git a/.travis.yml b/.travis.yml
index dc27ebf..2538954 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -52,10 +52,13 @@
       compiler: gcc
       env: CMAKE_FLAGS="-DWITH_SIMD=0"
 
+addons:
+  homebrew:
+    brewfile: true
+    update: true
+
 before_install:
   - if [ "$TRAVIS_OS_NAME" = "osx" ]; then
-      brew update &&
-      brew bundle &&
       ln -fs /usr/local/bin/gpg1 /usr/local/bin/gpg &&
       git clone --depth=1 https://github.com/libjpeg-turbo/gas-preprocessor.git ~/src/gas-preprocessor &&
       ln -fs /Applications/Xcode.app /Applications/Xcode72.app;