Update Optimism ChainID from Kovan to Goerli (#15115)

Hey y’all! As part of our Optimism Kovan to Goerli migration, we’re working to make sure the whole ecosystem is up to speed on where we’re at and what they can do to ensure they’re not running an out of date testnet. Today, we posted  a dev blog and a tweet thread about the migration and we were wondering if we could get a RT from you to maximize visibility and reach. Would also appreciate if you could forward this info on to any other projects in the Optimism Ecosystem you guys work with. Appreciate the boost if you’re able to help amplify!

shared/constants/network.js

@@ -23,7 +23,7 @@ export const KOVAN_CHAIN_ID = '0x2a';
 export const LOCALHOST_CHAIN_ID = '0x539';
 export const BSC_CHAIN_ID = '0x38';
 export const OPTIMISM_CHAIN_ID = '0xa';
-export const OPTIMISM_TESTNET_CHAIN_ID = '0x45';
+export const OPTIMISM_TESTNET_CHAIN_ID = '0x1a4';
 export const POLYGON_CHAIN_ID = '0x89';
 export const AVALANCHE_CHAIN_ID = '0xa86a';
 export const FANTOM_CHAIN_ID = '0xfa';