Bump langchain-text-splitters in /samples/langgraph-sql-agent

Bumps [langchain-text-splitters](https://github.com/langchain-ai/langchain) from 0.3.8 to 0.3.9.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-text-splitters==0.3.8...langchain-text-splitters==0.3.9)

---
updated-dependencies:
- dependency-name: langchain-text-splitters
  dependency-version: 0.3.9
  dependency-type: direct:production
...

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

Author: dependabot[bot]

samples/langgraph-sql-agent/requirements.txt

@@ -448,9 +448,9 @@ langchain-google-vertexai==2.0.27 \
     --hash=sha256:4637d64aea1803ecefbcf411587fce358afac52ff8e88cfe89615fcd92c3701d \
     --hash=sha256:7e8f7e8ef6d321b64d37fc1c9324a13a34b26882ec02f92c0a86329f18895fd9
     # via langgraph-sql-agent
-langchain-text-splitters==0.3.8 \
-    --hash=sha256:116d4b9f2a22dda357d0b79e30acf005c5518177971c66a9f1ab0edfdb0f912e \
-    --hash=sha256:e75cc0f4ae58dcf07d9f18776400cf8ade27fadd4ff6d264df6278bb302f6f02
+langchain-text-splitters==0.3.9 \
+    --hash=sha256:7cd1e5a3aaf609979583eeca2eb34177622570b8fa8f586a605c6b1c34e7ebdb \
+    --hash=sha256:cee0bb816211584ea79cc79927317c358543f40404bcfdd69e69ba3ccde54401
     # via langchain
 langgraph==0.5.1 \
     --hash=sha256:312d341979e38034dde60e08df53505b8a196619df1266d6eacf6b002a0a65a8 \