CollateralizationOracle - swapDeposit should call internal functions to remove/add deposits
Instead of calling `removeDeposit` and `addDeposit`, `swapDeposit` should call its internal sister functions `_removeDeposit` and `_addDeposit` to avoid running the `onlyGovernor` checks multiple times.\\n```\\n/// @notice Swap a PCVDeposit with a new one, for instance when a new version\\n/// of a deposit (holding the same token) is deployed.\\n/// @param \\_oldDeposit : the PCVDeposit to remove from the list.\\n/// @param \\_newDeposit : the PCVDeposit to add to the list.\\nfunction swapDeposit(address \\_oldDeposit, address \\_newDeposit) external onlyGovernor {\\n    removeDeposit(\\_oldDeposit);\\n    addDeposit(\\_newDeposit);\\n}\\n```\\n
Call the internal functions instead. addDeposit's and removeDeposit's visibility can then be changed from `public` to `external`.
```\\n/// @notice Swap a PCVDeposit with a new one, for instance when a new version\\n/// of a deposit (holding the same token) is deployed.\\n/// @param \\_oldDeposit : the PCVDeposit to remove from the list.\\n/// @param \\_newDeposit : the PCVDeposit to add to the list.\\nfunction swapDeposit(address \\_oldDeposit, address \\_newDeposit) external onlyGovernor {\\n    removeDeposit(\\_oldDeposit);\\n    addDeposit(\\_newDeposit);\\n}\\n```\\n