fix: TravisCI 34b14f21e9 (@pwpiwi)

.travis.yml

@@ -23,6 +23,7 @@ before_install:
     sudo apt-get update -qq;
     sudo apt-get install -y gcc-arm-none-eabi;
   elif [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
+    brew update;
     brew tap iceman1001/proxmark3;
   fi
 
@@ -36,7 +37,7 @@ install:
 before_script:
 
 script: 
-## for the time being we are satisfied if it can be build and then successfully started
+## start and run a test script
   if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then 
     proxmark3 -h ;
   elif [[ "$TRAVIS_OS_NAME" == "linux" ]]; then