Use sticky selenium/standalone-chrome:3.141.59-20210713

New version3.141.59-2021729 is causing problems, so we need
to make it sticky to use a known to work version.

Author: stronk7

selenium.chrome.yml

@@ -4,6 +4,6 @@ services:
     environment:
       MOODLE_DOCKER_BROWSER: chrome
   selenium:
-    image: "selenium/standalone-chrome${MOODLE_DOCKER_SELENIUM_SUFFIX}:3"
+    image: "selenium/standalone-chrome${MOODLE_DOCKER_SELENIUM_SUFFIX}:3.141.59-20210713"
     volumes:
         - /dev/shm:/dev/shm