composer install fails with PHP 8.0

[sbrl]

If I try to run composer install with a newer (and supported) version of PHP, I get an error:

$ composer install
Installing dependencies from lock file (including require-dev)
Verifying lock file contents can be installed on current platform.
Your lock file does not contain a compatible set of packages. Please run composer update.

  Problem 1
    - Root composer.json requires php ^7.3 but your php version (8.0.13) does not satisfy that requirement.
  Problem 2
    - blastcloud/guzzler is locked to version 1.6.0 and an update of this package was not requested.
    - blastcloud/guzzler 1.6.0 requires php ^7.1 -> your php version (8.0.13) does not satisfy that requirement.
  Problem 3
    - fzaninotto/faker is locked to version v1.9.2 and an update of this package was not requested.
    - fzaninotto/faker v1.9.2 requires php ^5.3.3 || ^7.0 -> your php version (8.0.13) does not satisfy that requirement.

Also, your documumentation makes mention of SQLite3 support, but does not detail anywhere what combination of environment variables in .env will enable this functionality. I'd suggest that documenting all the values in .env would be a valuable exercise for letting new users know how to configure it.