Python dependency: Update authlib requirement in /web/regression

Updates the requirements on [authlib](https://github.com/authlib/authlib) to permit the latest version.
- [Release notes](https://github.com/authlib/authlib/releases)
- [Changelog](https://github.com/authlib/authlib/blob/main/docs/changelog.rst)
- [Commits](authlib/authlib@v1.5.0...v1.6.0)

---
updated-dependencies:
- dependency-name: authlib
  dependency-version: 1.6.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -12,7 +12,7 @@
 # relevant packages.
 ###############################################################################
 
-Authlib==1.5.*
+Authlib==1.6.*
 azure-identity==1.23.0
 azure-mgmt-rdbms==10.1.0
 azure-mgmt-resource==23.3.0