fix: add bsc testnet etherscan api

Author: ameeshaagrawal

hardhat.config.ts

@@ -81,6 +81,7 @@ const config: HardhatUserConfig = {
       arbitrumTestnet: process.env.ARBISCAN_API_KEY || "",
       avalanche: process.env.SNOWTRACE_API_KEY || "",
       bsc: process.env.BSCSCAN_API_KEY || "",
+      bscTestnet: process.env.BSCSCAN_API_KEY || "",
       goerli: process.env.ETHERSCAN_API_KEY || "",
       mainnet: process.env.ETHERSCAN_API_KEY || "",
       optimisticEthereum: process.env.OPTIMISM_API_KEY || "",