Bump compat for GPUArraysCore to 0.2, (keep existing compat)

[fhagemann]

I also exchanged using GPUArraysCore with import GPUArraysCore and added the prefix GPUArraysCore everywhere where it is used (which seems to be only in one line in transpose.jl).

[fhagemann]

Failing Downgrade tests are due to FillArrays<0.13 not being supported in julia-1.11.
I also expect the tests to still run on [email protected] because StructArrays does not yet allow for [email protected].

[oschulz]

Tests still run on GPUArraysCore v0.2, some deps will need to update first.

[fhagemann]

#45 set the lowest version of FillArrays to 0.13 (probably because of julia-1.11 compatibility).
It should be 0.13.8 though. We should either revert #45 back to FillArrays 0.8.4 (and run downgrade on julia-1.10) or increase the lower bound to 0.13.8. For this PR, I have chosen the latter.

[fhagemann]

Basically, this PR does what #46 is proposing.
I would recommend to do both at once and make a patch release.

[oschulz]

Test still use the old GPUArraysCore and StructArrays, looks like some deps need to update first.

[fhagemann]

That's because of RadiationDetectorSignals.