fix: restore PHP 8.3 installs and align Pest CI with SQLite

[CodeWithDennis]

Summary

Follow-up to #141. Restores real PHP 8.3 support for composer create-project, and aligns the Pest GitHub Action with Larament’s SQLite defaults.

Problem

After #141 landed, Installation CI still failed on PHP 8.3 because composer.lock had resolved to Symfony 8.1, which requires PHP >=8.4.1.

That was a lockfile resolution issue — not a Laravel/Filament floor:

Package	PHP requirement
Laravel 13	^8.3
Pest 4	^8.3
Filament 5	^8.2

Larament correctly targets PHP 8.3+ (Laravel + Pest). Filament would allow 8.2, but that is irrelevant here.

Separately, .github/workflows/pest.yml started a MySQL service even though:

• .env.example defaults to DB_CONNECTION=sqlite
• phpunit.xml forces sqlite + :memory: for tests

So MySQL was unused setup noise.

Changes

PHP 8.3-compatible lockfile

• Regenerated composer.lock under a temporary PHP 8.3 platform constraint, then removed that platform config.
• Downgraded Symfony components from 8.1 → 7.4 (still valid for Laravel 13 and symfony/process: ^7.4.5 || ^8.0.5).
• Kept composer.json on php: ^8.3.
• Re-enabled PHP 8.3 in the Installation workflow matrix (8.3 / 8.4 / 8.5 × Ubuntu, macOS, Windows).
• README PHP note remains 8.3 or higher.

Pest workflow → SQLite

• Removed the MySQL service bootstrap from .github/workflows/pest.yml.
• Create database/database.sqlite before php artisan migrate so migrate matches .env.example.
• Tests continue to use in-memory SQLite via phpunit.xml.

Files

File	Change
composer.lock	Symfony 7.4 resolution for PHP 8.3 installs
composer.json	Confirm / keep php: ^8.3
.github/workflows/installation.yml	Include PHP 8.3 in matrix
.github/workflows/pest.yml	Drop MySQL; touch SQLite DB before migrate
README.md	PHP 8.3+ requirement note

Why this matters

create-project installs from the committed lockfile. If the lock drifts onto Symfony 8.x, PHP 8.3 users hit hard Composer failures even though Laravel 13 and Pest 4 officially support 8.3. This PR makes the lock match that support again, and makes Pest CI reflect the same SQLite stack users get by default.

Test plan

• Lockfile uses Symfony 7.4.x (no Symfony 8.1 platform blockers on PHP 8.3)
• Installation matrix includes PHP 8.3 / 8.4 / 8.5
• Pest workflow no longer starts MySQL; creates SQLite file for migrate
• CI green: Installation on PHP 8.3 across Ubuntu / macOS / Windows
• CI green: Pest shards without MySQL
• Optional: local composer create-project smoke on PHP 8.3