Update dependency textual to ^0.64.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
textual	^0.63 -> ^0.64.0

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Release Notes

Textualize/textual (textual)

### [`v0.64.0`](https://togithub.com/Textualize/textual/blob/HEAD/CHANGELOG.md#0640---2024-06-03) [Compare Source](https://togithub.com/Textualize/textual/compare/v0.63.6...v0.64.0) ##### Fixed - Fix traceback on exit [https://github.com/Textualize/textual/pull/4575](https://togithub.com/Textualize/textual/pull/4575) - Fixed `Markdown.goto_anchor` no longer scrolling the heading into view [https://github.com/Textualize/textual/pull/4583](https://togithub.com/Textualize/textual/pull/4583) - Fixed Footer flicker on initial focus [https://github.com/Textualize/textual/issues/4573](https://togithub.com/Textualize/textual/issues/4573)

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