versions: Upgrade to cloud-hypervisor v15.0

Quotes from the cloud-hypervisor release v15.0:

This release is the first in a new version numbering scheme to represent that
we believe Cloud Hypervisor is maturing and entering a period of stability.
With this new release we are beginning our new stability guarantees.

Other highlights from the latest release include: 1) Network device rate
limiting; 2) Support for runtime control of `virtio-net` guest offload;
3) `--api-socket` supports file descriptor parameter; 4) Bug fixes on
`virtio-pmem`, PCI BARs alignment, `virtio-net`, etc.; 5) Deprecation of
the "LinuxBoot" protocol for ELF and bzImage in the coming release.

Details can be found: https://github.com/cloud-hypervisor/cloud-hypervisor/releases/tag/v15.0

Note: The client code of cloud-hypervisor's OpenAPI is automatically
generated by `openapi-generator` [1-2]. As the API changes do not
impact usages in Kata, no additional changes in kata's runtime are
needed to work with the current version of cloud-hypervisor.

[1] https://github.com/OpenAPITools/openapi-generator
[2] https://github.com/kata-containers/kata-containers/blob/main/src/runtime/virtcontainers/pkg/cloud-hypervisor/README.md

Fixes: #1779

Signed-off-by: Bo Chen <chen.bo@intel.com>

src/runtime/virtcontainers/pkg/cloud-hypervisor/client/docs/NetConfig.md

@@ -15,6 +15,7 @@ Name | Type | Description | Notes
 **VhostSocket** | **string** |  | [optional] 
 **Id** | **string** |  | [optional] 
 **Fd** | **[]int32** |  | [optional] 
+**RateLimiterConfig** | [**RateLimiterConfig**](RateLimiterConfig.md) |  | [optional] 
 
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