Bump google.golang.org/grpc from 1.51.0 to 1.55.0

Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.51.0 to 1.55.0.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](https://github.com/grpc/grpc-go/compare/v1.51.0...v1.55.0)

---
updated-dependencies:
- dependency-name: google.golang.org/grpc
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/google.golang.org/grpc/balancer/balancer.go

@@ -279,6 +279,14 @@ type PickResult struct {
 	// type, Done may not be called.  May be nil if the balancer does not wish
 	// to be notified when the RPC completes.
 	Done func(DoneInfo)
+
+	// Metadata provides a way for LB policies to inject arbitrary per-call
+	// metadata. Any metadata returned here will be merged with existing
+	// metadata added by the client application.
+	//
+	// LB policies with child policies are responsible for propagating metadata
+	// injected by their children to the ClientConn, as part of Pick().
+	Metatada metadata.MD
 }
 
 // TransientFailureError returns e.  It exists for backward compatibility and