Raise min version to PHP 7.3, check compatibility PHP 8.3.

[terabytesoftw]

Q	A
Is bugfix?	no
New feature?	yes
Breaks BC?	no
Tests pass?	no

[what-the-diff]

PR Summary

• Improved Code Conformity
  The team has set a rule that all .yml file types must have an indentation of two spaces. This will help achieve a more consistent and readable code style across these files.

• Automated Build and Testing
  The addition of the .github/workflows/build.yml file signifies the setup of an automated system (GitHub Actions) that builds and tests the product whenever changes are made, ensuring our releases are more reliable and error-free.

• Updated Service Provider
  The removal of .travis.yml indicates a shift from Travis CI to another service provider for continuous integration (CI) tasks, reflecting changes in the team's production and deployment process.

• Enhanced Server Compatibility
  The requirement for PHP 7.3 and PHPUnit 9.6 or higher in composer.json suggests updated server requirements. This helps us to utilize newer features or improvements available in these versions.

• Improved Test Coverage
  The phpunit.xml.dist file has been updated to cover the ./src directory and use the latest schema valid for PHPUnit 9.3. This means that more of our code is now being tested for errors and performance.

• Refined Class Functionality
  The team has updated the Collection class to remove errors and improve functionality. This includes fixing a typo, modifying the behavior of the getData() method, and declaring that the offsetSet() method does not return any value.

• Simplified Tests
  In tests/CollectionTest.php, tests for inherited methods and irrelevant exception annotations were removed, decluttering the test environment and focusing only on pertinent tests.

• Standardized Test Methods
  The setUp() and tearDown() methods in tests/ModelCollectionTest.php and tests/TestCase.php have been modified to consistently return nothing (void), thereby minimizing potential disruption in testing operations.