enable experimental feature in zstd-sys

This will allow using zstd-static-linking-only  if enabled

Author: zaidoon1

librocksdb-sys/Cargo.toml

@@ -48,7 +48,7 @@ tikv-jemalloc-sys = { version = "0.5", features = [
     "unprefixed_malloc_on_supported_platforms",
 ], optional = true }
 lz4-sys = { version = "1.9", optional = true }
-zstd-sys = { version = "2.0", features = ["zdict_builder"], optional = true }
+zstd-sys = { version = "2.0", features = ["zdict_builder", "experimental"], optional = true }
 libz-sys = { version = "1.1", default-features = false, optional = true }
 bzip2-sys = { version = "0.1", default-features = false, optional = true }