adding protobuf-code feature to cargo.toml

Signed-off-by: limbooverlambda <[email protected]>

Cargo.toml

@@ -14,6 +14,7 @@ prometheus = ["prometheus/push", "prometheus/process"]
 # Enable integration tests with a running TiKV and PD instance.
 # Use $PD_ADDRS, comma separated, to set the addresses the tests use.
 integration-tests = []
+protobuf-codec = []
 
 [lib]
 name = "tikv_client"