JBSingleAllowance
Notes:
- 
member: sigDeadline Deadline on the permit signature.
 - 
member: amount The maximum amount allowed to spend.
 - 
member: expiration Timestamp at which a spender's token allowances become invalid.
 - 
member: nonce An incrementing value indexed per owner,token,and spender for each signature.
 - 
member: signature The signature over the permit data. Supports EOA signatures, compact signatures defined by EIP-2098, and contract signatures defined by EIP-1271.
 
struct JBSingleAllowance {
    uint256 sigDeadline;
    uint160 amount;
    uint48 expiration;
    uint48 nonce;
    bytes signature;
}