fix: add serde_json and rand workspace deps for soroban-sdk testutils

Author: Xhristin3

contract/Cargo.toml

@@ -17,6 +17,8 @@ license = "MIT"
 
 [workspace.dependencies]
 soroban-sdk = { version = "23.5.2", features = ["testutils"] }
+serde_json = "1.0"
+rand = "0.8"
 gathera-common = { path = "./common" }
 ticket_contract = { path = "./ticket_contract" }
 escrow_contract = { path = "./escrow_contract" }