Add missing timestamp_upb_reflection_proto alias

PiperOrigin-RevId: 862919795

Author: protobuf-github-bot

BUILD.bazel

@@ -272,6 +272,12 @@ alias(
     visibility = ["//visibility:public"],
 )
 
+alias(
+    name = "timestamp_upb_reflection_proto",
+    actual = "//src/google/protobuf:timestamp_upb_reflection_proto",
+    visibility = ["//visibility:public"],
+)
+
 alias(
     name = "type_upb_reflection_proto",
     actual = "//src/google/protobuf:type_upb_reflection_proto",