Update grpc-gateway dependency (#2311)

* chore(deps): Update grpc-gateway dependency

This fixes an issue which would allow an attacker to trigger a
(recovered) panic in the gateway handler.

* fix(server): Use cmp.Diff instead of assert.Equal

Testify is not great at handling protobuf types, and
was for some reason returning a diff here when in
reality there is none. Switch to go-cmp for the
comparison to remove the error.

sdk/pbs/controller/api/resources/authmethods/auth_method.pb.go

@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.27.1
+// 	protoc-gen-go v1.28.1
 // 	protoc        (unknown)
 // source: controller/api/resources/authmethods/v1/auth_method.proto