support regex that compatible with python re lib however apply more l… (#32676)

rust/sglang-server/Cargo.toml

@@ -34,7 +34,11 @@ core_affinity = "0.8"
 # the dynamo-tokenizers is deps on hf-hub, should bump version together
 dynamo-tokenizers = "1.5.3"
 flume = "0.12.0"
+itertools = "0.14"
 hf-hub = { version = "0.4", default-features = false }
-regex-syntax = "0.8"
 rmp-serde = "1"
 rmpv = { version = "1", features = ["with-serde"] }
+# Pinned EXACTLY: this crate's accepted grammar defines the
+# "anything Rust admits, Python can compile" invariant in `message::sampling`.
+# A minor bump can widen it and silently reopen a scheduler-killing hole.
+regex-syntax = "=0.8.11"