[BUG] Updating numba-cuda should invalidate disk caches

[tpn]

The disk-caching logic is currently tied to numba.__version__, such that the caches are invalidated when a numba version bump occurs. This seems like it should be changed to gate off numba_cuda.__version__ instead.

[Saad-Mallebhari]

@tpn
The cache key is built in numba/core/caching.py using numba.__version__. Since numba-cuda is now a separate package, bumping it alone won't invalidate stale caches.
The fix would be to include numba_cuda.__version__ in the cache key, something like:

import numba_cuda
cache_key = f"{numba.__version__}-{numba_cuda.__version__}"

Using both versions ensures caches invalidate on either package update,
not just numba core bumps.