This fixes the close button not being vertically aligned in the tab bar.


## Before
![screenshot-2024-01-15-18 13
49@2x](https://github.com/zed-industries/zed/assets/1185253/edf81b4d-a93a-461a-9835-4aba025cf337)

## After
![screenshot-2024-01-15-18 14
45@2x](https://github.com/zed-industries/zed/assets/1185253/2ae24c8c-9df3-4248-8566-fee6ce8602e0)


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Release Notes:

- Fixed close-tab button not being vertically aligned in the tab bar.