Fix kvproto dependencies build errs.

Signed-off-by: lucasliang <nkcs_lykx@hotmail.com>

Cargo.toml

@@ -69,7 +69,7 @@ ctor = "0.2"
 env_logger = "0.10"
 kvproto = { git = "https://github.com/pingcap/kvproto.git", default-features = false, features = [
   "protobuf-codec",
-] }
+], branch = "release-7.5" }
 raft = { git = "https://github.com/tikv/raft-rs", branch = "master", default-features = false, features = [
   "protobuf-codec",
 ] }