Remove inheritance that conflicts with upgradeable transpiler

contracts/mocks/BadBeacon.sol

@@ -2,13 +2,11 @@
 
 pragma solidity >=0.6.0 <0.8.0;
 
-import "../proxy/IBeacon.sol";
-
 contract BadBeaconNoImpl {
 }
 
-contract BadBeaconNotContract is IBeacon {
-    function implementation() external view override returns (address) {
+contract BadBeaconNotContract {
+    function implementation() external view returns (address) {
         return address(0x1);
     }
 }