fix: trimmed Empty protobuf definition

Signed-off-by: Matt Peterson <[email protected]>

Author: mattp-swirldslabs

protos/src/main/protobuf/blockstream.proto

@@ -16,6 +16,3 @@ message Block {
 message BlockResponse {
     int64 id = 1;
 }
-
-message Empty {
-}