try to install homebrew

Author: skvark

travis_config.sh

@@ -89,7 +89,7 @@ function pre_build {
 
     local CACHE_STAGE; (echo "$TRAVIS_BUILD_STAGE_NAME" | grep -qiF "final") || CACHE_STAGE=1
 
-    brew update-reset
+    /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
 
     #after the cache stage, all bottles and Homebrew metadata should be already cached locally
     if [ -n "$CACHE_STAGE" ]; then