grpc 1.78.0 dropped its rules_swift dependency, resolving the version
conflict (rules_swift 3.x vs 2.x) that forced SparklePlugin into a
separate workspace. This removes the rules_swift single_version_override.
Includes a patch for a known BCR bug (grpc/grpc#41438) where grpc 1.78.0
requests Python 3.14.0b2 but rules_python >= 1.6.0 replaced it with 3.14.
The patch backports the upstream fix (commit 459279b).
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>