Update dependency mkdocs to v1.5.3 (#571)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [mkdocs](https://togithub.com/mkdocs/mkdocs)
([changelog](https://www.mkdocs.org/about/release-notes/)) | patch |
`==1.5.2` -> `==1.5.3` |

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### ⚠ Dependency Lookup Warnings ⚠

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### Release Notes

<details>
<summary>mkdocs/mkdocs (mkdocs)</summary>

### [`v1.5.3`](https://togithub.com/mkdocs/mkdocs/releases/tag/1.5.3)

[Compare
Source](https://togithub.com/mkdocs/mkdocs/compare/1.5.2...1.5.3)

- Fix `mkdocs serve` sometimes locking up all browser tabs when
navigating quickly
([#&#8203;3390](https://togithub.com/mkdocs/mkdocs/issues/3390))

- Add many new supported languages for "search" plugin - update
lunr-languages to 1.12.0
([#&#8203;3334](https://togithub.com/mkdocs/mkdocs/issues/3334))

- Bugfix (regression in 1.5.0): In "readthedocs" theme the styling of
"breadcrumb navigation" was broken for nested pages
([#&#8203;3383](https://togithub.com/mkdocs/mkdocs/issues/3383))

- Built-in themes now also support Chinese (Traditional, Taiwan)
language
([#&#8203;3370](https://togithub.com/mkdocs/mkdocs/issues/3370))

- Plugins can now set `File.page` to their own subclass of `Page`. There
is also now a warning if `File.page` is set to anything other than a
strict subclass of `Page`.
([#&#8203;3367](https://togithub.com/mkdocs/mkdocs/issues/3367),
[#&#8203;3381](https://togithub.com/mkdocs/mkdocs/issues/3381))

Note that just instantiating a `Page` [sets the file
automatically](https://togithub.com/mkdocs/mkdocs/blob/f94ab3f62d0416d484d81a0c695c8ca86ab3b975/mkdocs/structure/pages.py#L34),
so care needs to be taken not to create an unneeded `Page`.

Other small improvements; see [commit
log](https://togithub.com/mkdocs/mkdocs/compare/1.5.2...1.5.3).

</details>

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.github/workflows/mkdocs-requirements.txt

@@ -5,7 +5,7 @@ livereload==2.6.3
 lunr==0.7.0.post1
 Markdown==3.4.4
 MarkupSafe==2.1.3
-mkdocs==1.5.2
+mkdocs==1.5.3
 mkdocs-macros-plugin==1.0.4
 mkdocs-material==9.2.7
 mkdocs-material-extensions==1.1.1