Rename test class to match filename

[athos-ribeiro]

Having phpunit test classes not matching their file names has been deprecated since phpunit 9 and was removed in phpunit 10.

• https://github.com/sebastianbergmann/phpunit/issues/4105
• https://github.com/sebastianbergmann/phpunit/issues/4621#issuecomment-797604984

[williamdes]

Fixes: #97

@athos-ribeiro can you add this to your PR description?

[athos-ribeiro]

Sure!

I did not see we had an issue open for this one. Thanks (done)!