use msg.sender rather than _msgSender() in FeeSplitter.receive

[code423n4]

Handle

TomFrench

Vulnerability details

Impact

Gas costs

Proof of Concept

In the receive function of FeeSplitter we check that the address sending ETH is the WETH contract:
https://github.com/code-423n4/2021-11-nested/blob/5d113967cdf7c9ee29802e1ecb176c656386fe9b/contracts/FeeSplitter.sol#L74

As we can safely say that the WETH contract will never send a metatransaction, we can just use msg.sender and avoid the extra gas costs of _msgSender()

Recommended Mitigation Steps

Replace _msgSender() with msg.sender