Bump authlib from 1.6.3 to 1.6.4

Bumps [authlib](https://github.com/authlib/authlib) from 1.6.3 to 1.6.4.
- [Release notes](https://github.com/authlib/authlib/releases)
- [Changelog](https://github.com/authlib/authlib/blob/main/docs/changelog.rst)
- [Commits](authlib/authlib@v1.6.3...v1.6.4)

---
updated-dependencies:
- dependency-name: authlib
  dependency-version: 1.6.4
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -2,7 +2,7 @@ aiofiles==24.1.0
 annotated-types==0.7.0
 anyio==4.9.0
 attrs==25.3.0
-Authlib==1.6.3
+Authlib==1.6.4
 certifi==2025.6.15
 cffi==2.0.0
 charset-normalizer==3.4.2