Bug report: testui keep failing with Chromedriver version error

[jpledref]

Describe the bug
UI tests with nightwatch fail by raising this message:

message: 'session not created: This version of ChromeDriver only supports Chrome version 114\n' +
         'Current browser version is 117.0.5938.88 with binary path /usr/bin/google-chrome',

This issue may block the merge of PRs. (See #1631 #1626 #1623)

To Reproduce
Steps to reproduce the behaviour or a link to the recipe / input used to cause the bug:

1. Create a new PR (or trigger github actions again)
2. pull_request jobs will run and this error will be shown

Expected behaviour
A job ending with a success.

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
Add any other context about the problem here.

The problem comes from an incompatibility between chromedriver npm package version and installed chromium version into the runner. Into pull_requests.yml, ubuntu-latest image is used.

=> We shall either pin this ubuntu version or install a pinned version of chromium into the job. Upgrading periodically chromedriver will tire us out.

[a3957273]

Fixed in #1700