Try with a full path...

Author: cwoffenden

.circleci/config.yml

@@ -35,7 +35,7 @@ commands:
           name: download chrome
           command: |
             # Try adding a dummy sound device for Chrome...
-            modprobe snd-dummy
+            /usr/sbin/modprobe snd-dummy
             # TODO: Make these part of the base image
             apt-get install -q -y libu2f-udev libvulkan1 xdg-utils
             # wget -O ~/chrome.deb https://dl.google.com/linux/direct/google-chrome-beta_current_amd64.deb