💄 — Use CSS media prefers-color-scheme on splash screen

Users using a dark theme on there OS will obviously have a lot of
chances to choose Kresus’ dark theme. But the theme is not initialized
on splash screen (whene you arrive on your Kresus).
Using `@media (prefers-color-scheme: dark)` on the splash screen avoid
hurting dark theme lovers’ eyes with a white background 🙂
4 jobs for prefers-color-scheme-at-splashboot in 1 minute and 41 seconds (queued for 3 seconds)
latest
Status Name Job ID Coverage
  Lint
failed lint #980604

00:01:41

 
  Build
skipped build #980605
 
  Test
skipped lint_history #980607
skipped test #980606
 
Name Stage Failure
failed
lint Lint
[1] ✖ 317 problems (0 errors, 317 warnings)
[1]
[1] yarn run -- eslint --cache ./server ./client ./tests exited with code 0
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
Running after_script
Uploading artifacts for failed job
Authenticating with credentials from /root/.docker/config.json
ERROR: Job failed: exit code 1