Fix Soldiity compiler warnings due to payable fallback function

[nategraf]

Warning (3628): This contract has a payable fallback function, but no receive ether function. Consider adding a receive ether function.
  --> lib/risc0-ethereum/contracts/src/relay/BonsaiRelayQueueWrapper.sol:26:1:
   |
26 | contract BonsaiRelayQueueWrapper is IBonsaiRelay, Proxy, Test {
   | ^ (Relevant source part starts here and spans across multiple lines).
Note: The payable fallback function is defined here.
  --> lib/openzeppelin-contracts/contracts/proxy/Proxy.sol:66:5:
   |
66 |     fallback() external payable virtual {
   |     ^ (Relevant source part starts here and spans across multiple lines).