Update Homebrew to workaround https://travis-ci.community/t/macos-build-fails-because-of-homebrew-bundle-unknown-command/7296/13

Author: palfrey

.travis.yml

@@ -45,6 +45,7 @@ jobs:
           - psqlodbc
           - sqliteodbc
           - postgresql
+          update: true # Workaround for bundle issue https://travis-ci.community/t/macos-build-fails-because-of-homebrew-bundle-unknown-command/7296/13
       env: SQLITE_DRIVER=/usr/local/opt/sqliteodbc/lib/libsqlite3odbc.dylib POSTGRES_DRIVER=/usr/local/opt/psqlodbc/lib/psqlodbca.so HOMEBREW_NO_INSTALL_CLEANUP=1
       before_script:
         - pg_ctl -D /usr/local/var/postgres start