Fix brew on mac finding GCC

Author: BillyONeal

azure-pipelines.yml

@@ -243,7 +243,7 @@ jobs:
       vmImage: 'macOS-10.13'
     steps:
     - script: |
-        brew install gcc-6
+        brew install gcc
         ./vcpkg/bootstrap-vcpkg.sh
         ./vcpkg/vcpkg install zlib openssl boost-system boost-date-time boost-regex websocketpp boost-thread boost-filesystem boost-random boost-chrono brotli
       displayName: Vcpkg install dependencies