Bump marshmallow from 3.26.1 to 3.26.2 in /samples/langgraph-sql-agent

Bumps [marshmallow](https://github.com/marshmallow-code/marshmallow) from 3.26.1 to 3.26.2.
- [Changelog](https://github.com/marshmallow-code/marshmallow/blob/3.26.2/CHANGELOG.rst)
- [Commits](marshmallow-code/marshmallow@3.26.1...3.26.2)

---
updated-dependencies:
- dependency-name: marshmallow
  dependency-version: 3.26.2
  dependency-type: direct:production
...

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

Author: dependabot[bot]

samples/langgraph-sql-agent/requirements.txt

@@ -574,9 +574,9 @@ markdown-it-py==4.0.0 \
     --hash=sha256:87327c59b172c5011896038353a81343b6754500a08cd7a4973bb48c6d578147 \
     --hash=sha256:cb0a2b4aa34f932c007117b194e945bd74e0ec24133ceb5bac59009cda1cb9f3
     # via rich
-marshmallow==3.26.1 \
-    --hash=sha256:3350409f20a70a7e4e11a27661187b77cdcaeb20abca41c1454fe33636bea09c \
-    --hash=sha256:e6d8affb6cb61d39d26402096dc0aee12d5a26d490a121f118d2e81dc0719dc6
+marshmallow==3.26.2 \
+    --hash=sha256:013fa8a3c4c276c24d26d84ce934dc964e2aa794345a0f8c7e5a7191482c8a73 \
+    --hash=sha256:bbe2adb5a03e6e3571b573f42527c6fe926e17467833660bebd11593ab8dfd57
     # via dataclasses-json
 mdurl==0.1.2 \
     --hash=sha256:84008a41e51615a49fc9966191ff91509e3c40b939176e643fd50a5c2196b8f8 \