chore(deps): bump langchain-community from 0.2.16 to 0.2.19 in /samples (#230)

Bumps [langchain-community](https://github.com/langchain-ai/langchain) from 0.2.16 to 0.2.19.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-community==0.2.16...langchain-community==0.2.19)

---
updated-dependencies:
- dependency-name: langchain-community
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Averi Kitsch <akitsch@google.com>

Author: dependabot[bot]

samples/index_tuning_sample/requirements.txt

@@ -1,3 +1,3 @@
-langchain-community==0.3.1
+langchain-community==0.2.19
 langchain-google-cloud-sql-pg==0.10.0
 langchain-google-vertexai==2.0.0

samples/langchain_on_vertexai/requirements.txt

@@ -1,5 +1,5 @@
 google-cloud-aiplatform[reasoningengine,langchain]==1.69.0
 google-cloud-resource-manager==1.12.5
-langchain-community==0.2.16
+langchain-community==0.2.19
 langchain-google-cloud-sql-pg==0.10.0
 langchain-google-vertexai==1.0.10

samples/requirements.txt

@@ -1,5 +1,5 @@
 google-cloud-aiplatform[reasoningengine,langchain]==1.69.0
 google-cloud-resource-manager==1.12.5
-langchain-community==0.2.16
+langchain-community==0.2.19
 langchain-google-cloud-sql-pg==0.10.0
 langchain-google-vertexai==1.0.10