BUG: Fix assert_frame_equal dtype handling when check_dtype=False (#61473)
Fixes a bug in `assert_frame_equal` where `DataFrames` with logically equal values but different dtypes (nullable vs non-nullable) would raise errors even with check_dtype=False. Now, when `check_dtype=False`, dtype mismatches won’t cause failures.

- [x] closes #61473 

 - [x] Tests added and passing

- [x] Pre-commit checks passing

- [x] Added entry to v3.0.0.rst


This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. hey @mroeschke, addressed the review. mind taking another look when you get a chance?