title: The repository 'http://dl.google.com/linux/chrome/deb stable Release' is not signed
body: <p>I have the following step in my CircleCi setup to install Google Chrome:</p>
  
  <pre><code>  - run:
        name: Install Chrome headless
        working_directory: /
        command: |
          wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add - &amp;&amp; \
            echo "deb http://dl.google.com/linux/chrome/deb/ stable main" &gt; /etc/apt/sources.list.d/google.list &amp;&amp; \
            apt-get update &amp;&amp; \
            apt-get install -y dbus-x11 google-chrome-unstable &amp;&amp; \
            rm -rf /var/lib/apt/lists/*
  </code></pre>
  
  <p>It stopped working and return the following error message:</p>
  
  <pre><code>W: GPG error: http://dl.google.com/linux/chrome/deb stable Release: The following signatures were invalid: EXPKEYSIG 1397BC53640DB551 Google Inc. (Linux Packages Signing Authority) &lt;linux-packages-keymaster@google.com&gt;
  W: The repository 'http://dl.google.com/linux/chrome/deb stable Release' is not signed.
  N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
  N: See apt-secure(8) manpage for repository creation and user configuration details.
  
  Reading package lists... Done
  
  
  Building dependency tree       
  
  
  Reading state information... Done
  
  The following additional packages will be installed:
    libappindicator3-1 libdbusmenu-gtk3-4 libindicator3-7
  Recommended packages:
    libu2f-udev
  The following NEW packages will be installed:
    dbus-x11 google-chrome-unstable libappindicator3-1 libdbusmenu-gtk3-4
    libindicator3-7
  0 upgraded, 5 newly installed, 0 to remove and 48 not upgraded.
  Need to get 60.4 MB of archives.
  After this operation, 214 MB of additional disk space will be used.
  WARNING: The following packages cannot be authenticated!
    google-chrome-unstable
  E: There were unauthenticated packages and -y was used without --allow-unauthenticated
  Exited with code 100
  </code></pre>
  
  <p>How can I fix that?</p>