update changelog for version 2.9.4 via release script

CHANGELOG.md

@@ -2,6 +2,24 @@
 
 Changelogs for versions not listed here can be found at https://github.com/DataDog/dd-trace-py/releases
 
+---
+
+## 2.9.4
+
+
+### New Features
+
+- langchain: This introduces support for `langchain==0.2.0` by conditionally patching the `langchain-community` module if available, which is an optional dependency for `langchain>=0.2.0`. See the langchain integration :ref: <span class="title-ref">docs\<langchain\></span> for more details.
+
+### Bug Fixes
+
+- langchain: This fix resolves an issue where the wrong langchain class name was being used to check for Pinecone vectorstore instances.
+- opentelemetry: Resolves circular imports raised by the OpenTelemetry API when the `ddcontextvars_context` entrypoint is loaded. This resolves an incompatibility introduced in `opentelemetry-api==1.25.0`.
+- redis: This fix resolves an issue in the redis exception handling where an UnboundLocalError was raised instead of the expected BaseException.
+- Code Security: Logs warning instead of throwing an exception in the native module if IAST is not enabled by env var.
+- langchain: This fixes an issue of langchain patching errors due to the `langchain-community` module becoming an optional dependency in `langchain>=0.2.0`. The langchain integration now conditionally patches `langchain-community` methods if it is available. See the langchain integration :ref: <span class="title-ref">docs\<langchain\></span> for more details.
+
+
 ---
 
 ## 2.9.1