Make `Ownable2Step.acceptOwnership` virtual (#3960)

CHANGELOG.md

@@ -11,6 +11,7 @@
  * `Strings`: add `toString` method for signed integers. ([#3773](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3773))
  * `MerkleProof`: optimize by using unchecked arithmetic. ([#3869](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3869))
  * `EnumerableMap`: add a `keys()` function that returns an array containing all the keys. ([#3920](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3920))
+ * `Ownable2Step`: make `acceptOwnership` public virtual to enable usecases that require overriding it. ([#3960](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3960))
 
 ### Deprecations
 

contracts/access/Ownable2Step.sol

@@ -49,7 +49,7 @@ abstract contract Ownable2Step is Ownable {
     /**
      * @dev The new owner accepts the ownership transfer.
      */
-    function acceptOwnership() external {
+    function acceptOwnership() public virtual {
         address sender = _msgSender();
         require(pendingOwner() == sender, "Ownable2Step: caller is not the new owner");
         _transferOwnership(sender);