Bump authlib from 1.6.0 to 1.6.4 in /samples/adk-sql-agent

Bumps [authlib](https://github.com/authlib/authlib) from 1.6.0 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@v1.6.0...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]

samples/adk-sql-agent/requirements.txt

@@ -20,9 +20,9 @@ attrs==25.3.0 \
     # via
     #   jsonschema
     #   referencing
-authlib==1.6.0 \
-    --hash=sha256:4367d32031b7af175ad3a323d571dc7257b7099d55978087ceae4a0d88cd3210 \
-    --hash=sha256:91685589498f79e8655e8a8947431ad6288831d643f11c55c2143ffcc738048d
+authlib==1.6.4 \
+    --hash=sha256:104b0442a43061dc8bc23b133d1d06a2b0a9c2e3e33f34c4338929e816287649 \
+    --hash=sha256:39313d2a2caac3ecf6d8f95fbebdfd30ae6ea6ae6a6db794d976405fdd9aa796
     # via google-adk
 cachetools==5.5.2 \
     --hash=sha256:1a661caa9175d26759571b2e19580f9d6393969e5dfca11fdb1f947a23e640d4 \