Add Symfony 7 & PHP 8.3 support, and `mapMultiple()` feature

What's Changed

• Allow Symfony 7 by @bocharsky-bw in #7
• Add PHP 8.3 support by @bocharsky-bw in #8
• Simplify CI config thanks to upstream changes by @bocharsky-bw in #10
• [ci] php-cs-fixer it up by @jrushlow in #14
• [dx] keep tooling in one place by @jrushlow in #13
• [CI] PHP CS Fixer it up by @bocharsky-bw in #12
• feat: Add mapMultiple method by @lxix in #15

New Contributors

• @bocharsky-bw made their first contribution in #7
• @jrushlow made their first contribution in #14
• @lxix made their first contribution in #15

Full Changelog: v0.1.4...v0.2.0