Update strong-bulldogs-buy.md

Author: frangio

.changeset/strong-bulldogs-buy.md

@@ -2,4 +2,4 @@
 'openzeppelin-solidity': minor
 ---
 
-`ERC1967Upgrade`: remove the existing, contract-wide, oz-upgrades-unsafe-allow natspec. ([#3971](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3971))
+`ERC1967Upgrade`: use more granular upgrade safety annotation. (Requires `@openzeppelin/upgrades-core@1.21.0`.)