Add TODO for debug print redaction

PiperOrigin-RevId: 560735493
diff --git a/src/google/protobuf/compiler/rust/message.cc b/src/google/protobuf/compiler/rust/message.cc
index 1e2a15b..5908269 100644
--- a/src/google/protobuf/compiler/rust/message.cc
+++ b/src/google/protobuf/compiler/rust/message.cc
@@ -271,6 +271,7 @@
       },
       R"rs(
         #[allow(non_camel_case_types)]
+        // TODO(b/291938599): Implement support for debug redaction
         #[derive(Debug)]
         pub struct $Msg$ {
           inner: $pbr$::MessageInner