fix: update js-stellar-sdk; use it correctly

I believe we were running into issues running these tests in CI. Since
they're not running in CI, they get stale quickly.

cmd/crates/soroban-spec-typescript/ts-tests/package.json

@@ -14,7 +14,7 @@
     "ava": "^5.3.1",
     "dotenv": "^16.3.1",
     "eslint": "^8.53.0",
-    "@stellar/stellar-sdk": "12.1.0",
+    "@stellar/stellar-sdk": "12.2.0",
     "typescript": "^5.3.3"
   },
   "ava": {

cmd/crates/soroban-spec-typescript/ts-tests/src/util.ts

@@ -1,15 +1,22 @@
 import { spawnSync } from "node:child_process";
 import { Address, Keypair } from "@stellar/stellar-sdk";
-import { basicNodeSigner } from "@stellar/stellar-sdk/ContractClient";
+import { basicNodeSigner } from "@stellar/stellar-sdk/contract";
 
-const rootKeypair = Keypair.fromSecret(spawnSync("./soroban", ["keys", "show", "root"], { shell: true, encoding: "utf8" }).stdout.trim());
+const rootKeypair = Keypair.fromSecret(
+  spawnSync("./soroban", ["keys", "show", "root"], {
+    shell: true,
+    encoding: "utf8",
+  }).stdout.trim(),
+);
 
 export const root = {
   keypair: rootKeypair,
   address: Address.fromString(rootKeypair.publicKey()),
-}
+};
 
 export const rpcUrl = process.env.SOROBAN_RPC_URL ?? "http://localhost:8000/";
-export const networkPassphrase = process.env.SOROBAN_NETWORK_PASSPHRASE ?? "Standalone Network ; February 2017";
+export const networkPassphrase =
+  process.env.SOROBAN_NETWORK_PASSPHRASE ??
+  "Standalone Network ; February 2017";
 
 export const signer = basicNodeSigner(root.keypair, networkPassphrase);