Update pragma for Address.sol util to ^0.8.1 upwards

[koolamusic]

Referencing this PR #3025 as @axic had mentioned In 0.8.0 version of solidity the account.code.length syntax is supported, but the compiler does not have the shortcut implemented. This means it will first extcodecopy the entire target contract and measure size afterwards.

Following the guidelines with pragma version in OZ, my recommendation would be to create a new PR to update the pragma to ^0.8.1
cc @Amxx

[frangio]

From #3025 (comment):

My vote in this particular case is to bump this pragma to 0.8.1.

• It's always good to remove assembly.
• 0.8.1 is already almost a year old, I expect most users on 0.8 are using newer versions.
• 0.8.0 to 0.8.1 is unlikely to be very disruptive.

It should be noted as a breaking change in the changelog.