Update CHANGELOG.md

Author: ananthsub

CHANGELOG.md

@@ -206,6 +206,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed a bug in the binary search mode of auto batch size scaling where exception was thrown if the first trainer run resulted in OOM ([#8954](https://github.com/PyTorchLightning/pytorch-lightning/pull/8954))
 
 
+- Fixed typehint for `accumulate_grad_batches` in the `Trainer` constructor ([#9071](https://github.com/PyTorchLightning/pytorch-lightning/pull/9071))
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 ## [1.4.3] - 2021-08-17
 
 - Fixed plateau scheduler stepping on incomplete epoch ([#8861](https://github.com/PyTorchLightning/pytorch-lightning/pull/8861))