Bump authlib from 1.4.0 to 1.6.6 in /requirements

Bumps [authlib](https://github.com/authlib/authlib) from 1.4.0 to 1.6.6.
- [Release notes](https://github.com/authlib/authlib/releases)
- [Changelog](https://github.com/authlib/authlib/blob/main/docs/changelog.rst)
- [Commits](authlib/authlib@v1.4.0...v1.6.6)

---
updated-dependencies:
- dependency-name: authlib
  dependency-version: 1.6.6
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements/install.txt

@@ -18,7 +18,7 @@ argon2-cffi-bindings==21.2.0
     # via argon2-cffi
 async-timeout==5.0.1
     # via redis
-authlib==1.4.0
+authlib==1.6.6
     # via bemserver-api (pyproject.toml)
 bemserver-core==0.21.0
     # via bemserver-api (pyproject.toml)