Fix PHP 8.4 deprecation warnings for implicitly nullable parameters

[khoaofgod]

Proposed changes

This PR fixes the PHP 8.4 deprecation warnings related to implicitly nullable parameters. In PHP 8.4, parameters with a default value of null must be explicitly marked as nullable using the '?' prefix.

Fixes #924 and #926

Changes:

1. Fixed Redis Config::setDatabase() method (issue PHP8.4 Deprecation message #924)
2. Fixed PhpfastcacheIOException constructor (issue PHP 8.4 Deprecated Warning: Implicitly nullable parameter $previous in PhpfastcacheIOException::__construct #926)
3. Fixed additional similar occurrences in:
   • PhpfastcacheCorruptedDataException constructor
   • Psr16Adapter constructor
   • ClusterAggregator::aggregateDriverByName
   • AggregatorInterface::aggregateDriverByName
   • CacheContract::get and __invoke methods

These changes ensure compatibility with PHP 8.4 while maintaining backward compatibility with PHP 8.0+.

Types of changes

What types of changes does your code introduce to Phpfastcache?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• Improvement (non-breaking change which improves an existing code/behavior)
• Deprecated third party dependency update
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation/Typo/Resource update that does not involve any code modification

Agreement

I have read the CONTRIBUTING and CODING GUIDELINE docs

Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[Geolim4]

Ignore Travis fails as Travis has to be removed asap.