Wait for 5 confirmations before veryfing TokenholderGovernor

Without the change, the deployment/verification was logging:
```
Verifying contract 0x... on Etherscan...
Nothing to compile
NomicLabsHardhatPluginError: Failed to send contract verification request.
Endpoint URL: https://api-goerli.etherscan.io/api
Reason: The Etherscan API responded that the address 0x... does not have
bytecode.
This can happen if the contract was recently deployed and this fact hasn't
propagated to the backend yet.
Try waiting for a minute before verifying your contract. If you are invoking
this from a script, try to wait for five confirmations of your contract
deployment transaction before running the verification subtask.
```

Author: michalinacienciala

deploy/31_deploy_tokenholder_governor.ts

@@ -24,6 +24,11 @@ const func: DeployFunction = async function (hre: HardhatRuntimeEnvironment) {
   })
 
   if (hre.network.tags.etherscan) {
+    await hre.ethers.provider.waitForTransaction(
+      timelock.transactionHash,
+      5,
+      300000
+    )
     await helpers.etherscan.verify(
       timelock,
       "contracts/governance/TokenholderGovernor.sol:TokenholderGovernor"