PSR-4 Compliance Issue

[awadood]

The users with composer 2 are unable to use this package because of PSR-4 incompatibility. The following two classes from payum/iso4217 do not comply with PSR-4.

Payum\ISO4217\Tests\CurrencyTest
Payum\ISO4217\Tests\ISO4217Test

Solution:

Move both classes to a new directory "Tests" inside iso4217. 

[awadood]

@pierredup @makasim

[awadood]

@makasim @pierredup @StudioMaX @markitosgv it is requested to look into the issue. It is simply an obstacle for moving to Composer 2. Solution is really simple too which is already aforementioned. Thanks

[pierredup]

@awadood This package is deprecated and replaced with the original package (see Payum/Payum#879).

Also, this should not prevent you from using Composer 2, as the affected files are just unit tests which shouldn't be loaded anyway, and composer will just generate a warning and not prevent the installation of the package