Remove address override

[ericglau]

Closes #767

Remove overriding the contract address on deployments, since ethers.js's deploy function already calculates the address for the create operation.

[frangio]

We used to do something slightly different. I can't see what the difference would be though.

openzeppelin-upgrades/packages/plugin-hardhat/src/utils/deploy.ts

Line 12 in d666753

const { address, deployTransaction } = await factory.deploy(...args);

[ericglau]

We used to do something slightly different. I can't see what the difference would be though.

openzeppelin-upgrades/packages/plugin-hardhat/src/utils/deploy.ts

Line 12 in d666753

const { address, deployTransaction } = await factory.deploy(...args);

ethers v6 needs a different approach:

• deployTransaction can be null in the returned type (but should not be null here since it was a deployment)
• address is not a field so we need to await getAddress()