Balance check for swapToken in ShortLongSpell#_deposit is incorrect and will result in nonfunctional contract

Summary

The balance checks on ShortLongSpell#_withdraw are incorrect and will make contract basically nonfunctional

Vulnerability Detail

swapToken is always vault.uToken. borrowToken is always required to be vault.uToken which means that swapToken == borrowToken. This means that the token borrowed is always required to be swapped.

ShortLongSpell.sol#L83-L89

    uint256 strTokenAmt = _doBorrow(param.borrowToken, param.borrowAmount);

    // 3. Swap borrowed token to strategy token
    IERC20Upgradeable swapToken = ISoftVault(strategy.vault).uToken();
    // swapData.fromAmount = strTokenAmt;
    PSwapLib.megaSwap(augustusSwapper, tokenTransferProxy, swapData);
    strTokenAmt = swapToken.balanceOf(address(this)) - strTokenAmt; <- @audit-issue will always revert on swap

Because swapToken == borrowToken if there is ever a swap then the swapToken balance will decrease. This causes L89 to always revert when a swap happens, making the contract completely non-functional