feat: Modernize Project Dependencies and PHP Compatibility

[iamsquido]

Fixes #5

Modernization of Project Dependencies and PHP Compatibility

Overview

This pull request comprehensively updates the project to support modern PHP and Symfony versions, addressing technical debt and improving overall project sustainability.

Key Changes

• Updated PHP requirement from >=5.6 to >=8.1
• Upgraded Symfony components from ^3 to ^7.0
• Updated PHPUnit from ^5 to ^11.0
• Migrated from SwiftMailer to Symfony Mailer
• Updated Guzzle from ^6 to ^7.0
• Modernized Travis CI configuration

Detailed Modifications

• 🔧 composer.json: Updated all dependencies to latest versions
• 🔧 CrawlConfiguration.php: Fixed TreeBuilder instantiation for Symfony 7 compatibility
• 🧪 Unit Tests: Replaced deprecated PHPUnit annotations with modern method calls
• 🔧 phpunit.xml.dist: Updated configuration for PHPUnit 11.x
• 🔧 .travis.yml: Updated PHP versions to [8.1, 8.2, 8.3]
• 📧 Email Components: Migrated from SwiftMailer to Symfony Mailer

Migration Benefits

• Improved security with latest PHP version
• Better performance and modern language features
• Up-to-date dependencies with long-term support
• Enhanced type safety and code quality

Notes

• Requires PHP 8.1+ environment for full compatibility
• Recommended to run comprehensive tests after deployment

Testing Recommendations

1. Verify all dependencies install correctly
2. Run full test suite
3. Test email functionality
4. Validate SMTP configuration