Bump docker-compose to 1.25.2

Bump docker-compose from 1.25.1-rc1 to 1.25.1

Use Symfony 4.4 by default

Update actions/checkout to v2

Switch back to quay.io

GitHub Packages requires auth even for pulling, so it's not ideal for a public registry.

Switch to GitHub Actions / GitHub Packages

* 'master' of github.com:api-platform/api-platform:
  Revert "Skip vulcain headers from varnish request"

Revert "Skip vulcain headers from varnish request"

Add healthcheck php-fpm

Skip vulcain headers from varnish request

Co-authored-by: Teoh Han Hui <teohhanhui@gmail.com>

Replace h2-proxy by Vulcain

Preserve DX, as user is likely to just enter "localhost" in the browser's address bar

Add mercure.jwtKey

Bump deps

I got an `Unauthorized error` and figured out I didn't set the Mercure JWT key. I propose to add the key to `values.yaml` so it will be less easy to miss.

Bump APCu to 5.1.18

fixed broken link for LICENSE file

Co-Authored-By: Antoine Bluchet <soyuka@users.noreply.github.com>