Update to ROCm v6.2.4

[VlaDexa]

I think tests for this are kinda non existent at this moment, so it only ran one.

Running unittests src/lib.rs (target/debug/deps/cubecl_hip_sys-bc038986488f0a05)

running 1 test
test tests::test_launch_kernel_end_to_end ... ok

Also your suggested test command cargo xtask test --features rocm_622 wouldn't work on any other feature, like mine (rocm_624), because rocm_622 is set by default, and it name-clashes with the other version. That's also why I put 6.2.4 in the default.

[VlaDexa]

With the change to CI, it will check correctness only of the latest rocm binding, which may be undesired. I've opened issue #4 for discussion of this problem.

[syl20bnr]

Thank you !
I am going to update the versioning scheme and the README accordingly.