Upcoming change on Bazel support

[veb...@google.com]

Hi gRPC community,

gRPC Core started following the Foundational C++ policy a couple of years ago, which changes the supported platforms and build systems. As a result, gRPC will drop Bazel 5.x support in gRPC 1.60. (Note that this doesn't apply to other gRPC implementations such as gRPC Java or Go)

The relevant policy is as follows:

- We will support the latest Bazel release (excluding pre-releases), which Bazel calls their Active release.
- We will support the previous major version release for at least 6 months after it transitions into maintenance mode.

Bazel 5 has already moved into maintenance mode, so gRPC is now dropping support for it. We will also drop support for Bazel 6 in the future, 6 months after it goes into maintenance mode. (Read this to know more about Bazel's release cadence)

If you have any issues or concerns about this change, please let us know.

Regards,

Esun.