CI builds fail in Chromium.

[the-t-in-rtf]

Describe the bug

GitHub Actions now supports Chromium as well as Chrome, but the xvfb-run setup we use commonly in CI doesn't seem to work for Chromium. We get errors like:

not ok 11 Chromium - [undefined ms] - error
    ---
        message: >
            Error: Browser exited unexpectedly
            Non-zero exit code: 1
            Stderr: 
             mkdir: cannot create directory ‘/run/user/1001’: Permission denied
            No protocol specified
            [2021:2021:0215/090623.927454:ERROR:browser_main_loop.cc(1438)] Unable to open X display.
            
            
        browser log: |
            [object Object]
            [object Object]
            [object Object]
    ...

I tried adding the option to run Chromium using the chrome command-line arguments, but that didn't help. I'm creating this issue in case others encounter it and either want to look into it further or simply need a workaround.

Speaking of which, the workaround is to simply skip Chromium as illustrated here.