Fix protobuf generated srcs to include all sources (#2676)

diff --git a/proto/protobuf/proto.bzl b/proto/protobuf/proto.bzl
index e3ef70e..959d0c1 100644
--- a/proto/protobuf/proto.bzl
+++ b/proto/protobuf/proto.bzl
@@ -233,7 +233,7 @@
         ),
         output_hash = output_hash,
     )
-    providers.append(OutputGroupInfo(rust_generated_srcs = [lib_rs]))
+    providers.append(OutputGroupInfo(rust_generated_srcs = srcs))
     return providers
 
 def _rust_protogrpc_library_impl(ctx, is_grpc):