safeApprove of openZeppelin is deprecated

[code423n4]

Handle

robee

Vulnerability details

You use safeApprove of openZeppelin although it's deprecated.
(see https://github.com/OpenZeppelin/openzeppelin-contracts/blob/566a774222707e424896c0c390a84dc3c13bdcb2/contracts/token/ERC20/utils/SafeERC20.sol#L38)
You should change it to increase/decrease Allowance as OpenZeppilin says.
This appears in the following locations in the code base:

    Deprecated safeApprove in CreditLine.sol line 646: IERC20(_collateralAsset).approve(_strategy, _amount); 
    Deprecated safeApprove in CreditLine.sol line 774: IERC20(_borrowAsset).approve(_defaultStrategy, _amount); 
    Deprecated safeApprove in Controller.sol line 195: IERC20(_token).safeApprove(onesplit, 0); 
    Deprecated safeApprove in Controller.sol line 196: IERC20(_token).safeApprove(onesplit, _amount); 
    Deprecated safeApprove in Strategy.sol line 41: // IERC20(token).approve(mcd_join_eth_a, uint256(-1)); 
    Deprecated safeApprove in SavingsAccount.sol line 171: IERC20(_token).safeApprove(_newStrategy, _tokensReceived); 
    Deprecated safeApprove in SavingsAccountUtil.sol line 60: IERC20(_token).safeApprove(_approveTo, _amount); 
    Deprecated safeApprove in AaveYield.sol line 293: IERC20(asset).approve(lendingPool, 0); 
    Deprecated safeApprove in AaveYield.sol line 294: IERC20(asset).approve(lendingPool, amount); 
    Deprecated safeApprove in AaveYield.sol line 303: IERC20(IWETHGateway(wethGateway).getAWETHAddress()).approve(wethGateway, amount); 
    Deprecated safeApprove in AaveYield.sol line 320: IERC20(aToken).approve(lendingPool, amount); 
    Deprecated safeApprove in CompoundYield.sol line 207: IERC20(asset).approve(cToken, 0); 
    Deprecated safeApprove in CompoundYield.sol line 208: IERC20(asset).approve(cToken, amount); 
    Deprecated safeApprove in YearnYield.sol line 206: IERC20(asset).approve(vault, 0); 
    Deprecated safeApprove in YearnYield.sol line 207: IERC20(asset).approve(vault, amount); 

[ritik99]

Duplicate of #2