update to solc@0.5.16

update waffle version and fix deprecations

move CI from circle to github actions

contracts/UniswapV2ERC20.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 import "./interfaces/IUniswapV2ERC20.sol";
 import "./libraries/SafeMath.sol";

contracts/UniswapV2Exchange.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 import "./interfaces/IUniswapV2Exchange.sol";
 import "./UniswapV2ERC20.sol";

contracts/UniswapV2Factory.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 import "./interfaces/IUniswapV2Factory.sol";
 import "./UniswapV2Exchange.sol";

contracts/interfaces/IERC20.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 interface IERC20 {
     event Transfer(address indexed from, address indexed to, uint value);

contracts/interfaces/IUniswapV2ERC20.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 interface IUniswapV2ERC20 {
     event Transfer(address indexed from, address indexed to, uint value);

contracts/interfaces/IUniswapV2Exchange.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 interface IUniswapV2Exchange {
     event Mint(address indexed sender, uint amount0, uint amount1);

contracts/interfaces/IUniswapV2Factory.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 interface IUniswapV2Factory {
     event ExchangeCreated(address indexed token0, address indexed token1, address exchange, uint256);

contracts/libraries/Math.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 library Math {
     function min(uint x, uint y) internal pure returns (uint z) {

contracts/libraries/SafeMath.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 library SafeMath {
     function add(uint x, uint y) internal pure returns (uint z) {

contracts/libraries/UQ112x112.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 library UQ112x112 {
     uint224 constant Q112 = 2**112;

contracts/test/GenericERC20.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.15;
+pragma solidity =0.5.16;
 
 import "../UniswapV2ERC20.sol";