fix: use prost 0.12 from workspace to avoid version conflicts

Update fluss-rs to use prost from workspace instead of direct version
specification. This prevents version conflicts between prost 0.12 (needed
by protox) and prost 0.14 (previously specified). Added prost-types to
workspace for consistency.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: luoyuxia

Cargo.toml

@@ -42,3 +42,5 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 opendal = "0.53"
 jiff = { version = "0.2" }
+prost = "0.12"
+prost-types = "0.12"

crates/fluss/Cargo.toml

@@ -49,7 +49,7 @@ futures = "0.3"
 clap = { workspace = true }
 crc32c = "0.6.8"
 linked-hash-map = "0.5.6"
-prost = "0.14"
+prost = { workspace = true }
 rand = "0.9.1"
 serde = { workspace = true, features = ["rc"] }
 serde_json = { workspace = true }