Explicitly install libsecret-1-dev for travis

Author: alanz

.travis.yml

@@ -20,6 +20,8 @@ before_install:
       export DISPLAY=':99.0'
       /usr/bin/Xvfb :99 -screen 0 1024x768x24 > /dev/null 2>&1 &
     fi
+  - sudo apt-get update
+  - sudo apt-get -y install  libsecret-1-dev
 install:
 - npm ci
 - npm run vscode:prepublish