Use assertions rather than printing in tests

[joewallwork]

these tests will most likely fail with the intel compiler and possibly different version of gfortran. The default output is > quite different for both. We should think of another way to do this.

We could add something like the resnet test?>

https://github.com/Cambridge-ICCS/FTorch/blob/b40b03d4c39f607de754d34991a92703ccc36eb3/examples/2_ResNet18/resnet_infer_fortran.f90#L186C15-L214

Originally posted by @TomMelt in https://github.com/Cambridge-ICCS/FTorch/pull/136#discussion_r1652313394