Add support for PHP 8.4

[pataar]

Fixes the Explicit nullable param type deprecation warnings and upgrades the test suite to include PHP 8.4.

[pataar]

@ankitpokhrel Friendly ping :)

[genintho]

@ankitpokhrel friendly ping

[demmmmios]

@ankitpokhrel please 🙌

[LukasVaculcik]

This would be really nice <3

[Copilot]

Pull Request Overview

This PR adds support for PHP 8.4 by fixing deprecated nullable parameter type declarations. In PHP 8.4, using string $param = null is deprecated in favor of the explicit nullable syntax ?string $param = null. The PR updates all affected method signatures across the codebase and extends CI testing to include PHP 8.4.

Key Changes:

• Updated method signatures to use explicit nullable type syntax (?string instead of string = null)
• Extended GitHub Actions CI matrix to test against PHP 8.4
• Updated code coverage reporting to use PHP 8.4 as the reference version

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/Tus/Client.php	Updated file() method signature to use explicit nullable type for $name parameter
src/Response.php	Updated download() method signature to use explicit nullable type for $name parameter
src/File.php	Updated __construct() and setMeta() method signatures to use explicit nullable types
src/Config.php	Updated get() method signature to use explicit nullable type for $key parameter
src/Cache/FileStore.php	Updated __construct() and lock() method signatures to use explicit nullable types
.github/workflows/ci.yml	Added PHP 8.4 to test matrix and updated coverage reporting condition

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.60%. Comparing base (d431916) to head (340fc45).

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #452      +/-   ##
============================================
- Coverage     99.60%   99.60%   -0.01%     
  Complexity      362      362              
============================================
  Files            20       20              
  Lines          1016     1007       -9     
============================================
- Hits           1012     1003       -9     
  Misses            4        4              

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