chore(release): 6.0.0 [skip ci]

# [6.0.0](v5.1.0...v6.0.0) (2024-05-19)

### Bug Fixes

* type when merging optional properties of a record ([fa9ace2](fa9ace2))

### Build System

* remove typing support for typescript<4.7 ([f2f5956](f2f5956))

### Features

* allow restricting what types can be passed in as parameters ([69e9ba3](69e9ba3)), closes [#305](#305)
* remove deprecated type DeepMergeLeafHKT ([1982e56](1982e56))
* undefined will no longer replace defined values by default ([9c86605](9c86605))

### Performance Improvements

* remove BlacklistedRecordProps ([19d4944](19d4944))

### BREAKING CHANGES

* remove deprecated type DeepMergeLeafHKT
* undefined will no longer replace defined values by default
* The order of the generics of `deepmergeCustom`
and `deepmergeIntoCustom` have changed. If you are passing generics
to these functions you need to update them.
* remove typing support for typescript<4.7