travis: update the homebrew db We need to make sure we are asking for the current version of packages, or we might get 404s from the download service.
diff --git a/script/install-deps-osx.sh b/script/install-deps-osx.sh
index c2e0162..a0216e9 100755
--- a/script/install-deps-osx.sh
+++ b/script/install-deps-osx.sh
@@ -2,4 +2,5 @@
set -x
+brew update
brew install libssh2 cmake