Enable zstd feature for arrow-ipc to fix test_spill_compression test

The upstream Fix Arrow Spill Underrun (apache#20159) commit added a spill
compression test that uses SpillCompression::Zstd, but the zstd feature
was not enabled for arrow-ipc. Add it to fix the test failure.

https://claude.ai/code/session_01HUNF5yJU4aFrysyRPTnnSw

Author: claude

Cargo.toml

@@ -101,6 +101,7 @@ arrow-flight = { version = "57.1.0", features = [
 ] }
 arrow-ipc = { version = "57.1.0", default-features = false, features = [
     "lz4",
+    "zstd",
 ] }
 arrow-ord = { version = "57.1.0", default-features = false }
 arrow-schema = { version = "57.1.0", default-features = false }