chore: update testnet contract ID in NETWORKS constant and README

Author: MarcusDavidG

src/index.ts

@@ -17,7 +17,7 @@ export const NETWORKS = {
   testnet: {
     rpcUrl: "https://soroban-testnet.stellar.org",
     networkPassphrase: "Test SDF Network ; September 2015",
-    contractId: "CAYTIFPD6RFWVHMK5SPPUUIWWAAANHKOJB6GOAJS5SR5MBKZMEY2UODZ",
+    contractId: "CBJ7WNBHCO5LKM7LW33D7HUT7WZI5OROVPC7IJL3A6NT6HMVJ4XUWPHJ",
   },
   mainnet: {
     rpcUrl: "https://mainnet.sorobanrpc.com",