Describe the bug

The union type float|int in the function definition of Filter::numberFilter() is flagged as a syntax error, when using PHP 7.4.

Union types are only valid in PHP8.0 and above, but PHP 7.4 is being supported in composer.json.

To Reproduce
Call Filter::numberFilter() while using PHP 7.4.

Expected behavior
There should not be a syntax error.

Exceptions
This works fine in PHP8.0. So maybe remove all use of union types or make PHP8.0 the minimum requirement?

Additional context
None.