Update Alchemy URL endpoint for mainnet (#5052).

Author: ricmoo

src.ts/providers/provider-alchemy.ts

@@ -42,7 +42,7 @@ const defaultApiKey = "_gg7wSSi0KMBsdKnGVfHDueq6xMB9EkC"
 function getHost(name: string): string {
     switch(name) {
         case "mainnet":
-            return "eth-mainnet.alchemyapi.io";
+            return "eth-mainnet.g.alchemy.com";
         case "goerli":
             return "eth-goerli.g.alchemy.com";
         case "sepolia":