Relax tolerances for FP8 unit test only for ROCm + FP16 (#7373)
Relaxing the tolerance values to enable the below unit test, with FP16
data type on ROCm
`unit/runtime/half_precision/test_fp8.py::TestFp8ComposabilityAcrossZero::test[fp16]
`
```
# Relax tolerance only for ROCm + FP16
if is_rocm_pytorch() and model_dtype == torch.float16:
rtol, atol = 3e-07, 3e-05
```
cc: @jithunnair-amd