feat: update starknet example (#352)

Author: Riateche

pages/price-feeds/use-real-time-data/starknet.mdx

@@ -160,7 +160,7 @@ const priceId =
 const currentPrices = await connection.getLatestPriceFeeds([priceId]);
 
 // Convert the price update to Starknet format.
-const pythUpdate = ByteBuffer.fromHex(currentPrices[0].vaa);
+const pythUpdate = ByteBuffer.fromBase64(currentPrices[0].vaa);
 ```
 
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