Read the full announcement in the forum or check out the changelog.

• Now supports both Solidity 0.6 and 0.7. Compiling with solc 0.7 will result in warnings. Install the solc-0.7 tag to compile without warnings.
• TimelockController: added a contract to augment access control schemes with a delay. (#2354)
• Address: added functionStaticCall, similar to the existing functionCall. (#2333)
• EnumerableSet: added Bytes32Set, for sets of bytes32. (#2395)