Update src/lightning/pytorch/CHANGELOG.md

Author: SkafteNicki

src/lightning/pytorch/CHANGELOG.md

@@ -13,9 +13,6 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - WeightAveraging callback that wraps the PyTorch AveragedModel class ([#20545](https://github.com/Lightning-AI/pytorch-lightning/pull/20545))
 
 
-- Added support for general mappings being returned from `training_step` when using manual optimization ([#21011](https://github.com/Lightning-AI/pytorch-lightning/pull/21011))
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 - Added `save_on_exception` option to `ModelCheckpoint` Callback ([#20916](https://github.com/Lightning-AI/pytorch-lightning/pull/20916))