Fix the `Size` constructor arguments in `DeclarationBlock`

[Oliver Klee]

This will fix the following PHPStan warning:

			message: "#^Class Sabberworm\\\\CSS\\\\Value\\\\Size constructor invoked with 5 parameters, 1\\-4 required\\.$#"
			count: 2
			path: ../src/RuleSet/DeclarationBlock.php

Note: We'll need to check which argument is superfluous. It's not the last one (the line number).