[master] 608b5ac05 Stab at fixing macos travis job

[Federico G. Schwindt]

commit 608b5ac05ccab5e39ef720bdf33f49e74eb211f5
Author: Federico G. Schwindt <fgsch at lodoss.net>
Date:   Sat Mar 7 19:23:25 2020 +0000

    Stab at fixing macos travis job

diff --git a/.travis.yml b/.travis.yml
index f8a432b8a..b4154d50e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -77,6 +77,7 @@ jobs:
             - docutils
             - nghttp2
             - sphinx-doc
+          update: true
       before_script:
         - export PATH="/usr/local/opt/sphinx-doc/bin:$PATH"
         - ./autogen.sh