⚡️ Optimize zero point in expWad

[engn33r]

Description

This is the same optimization described in pcaversaccio/snekmate#189

This PR is for a very small optimization that is possible by increasing the range of values that will take the short logic path of expWad() and return 0. I am not sure how the previously chosen value of -42139678854452767551 was selected, but these tests demonstrate the actual turning point when the result of the current expWad() implementation transitions from 1 to 0.

function testExpWad() public {
    assertEq(FixedPointMathLib.expWad(-41446531673892822312), 1);
    assertEq(FixedPointMathLib.expWad(-41446531673892822313), 0);
}

Checklist

Ensure you completed all of the steps below before submitting your pull request:

• Ran forge fmt?
• Ran forge snapshot?
• Ran forge test?

Pull requests with an incomplete checklist will be thrown out.