Add opentelemetry-sdk as a dependency

temporalio 1.23.0+ internally imports opentelemetry-sdk via
contrib.openai_agents → contrib.opentelemetry. Since we pin
temporalio>=1.18.2,<2 and need to support newer versions for
CVE fixes, opentelemetry-sdk must be an explicit dependency.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: danielmillerp

pyproject.toml

@@ -49,6 +49,8 @@ dependencies = [
     "claude-agent-sdk>=0.1.0",
     "anthropic>=0.40.0",
     "langgraph-checkpoint>=2.0.0",
+    "opentelemetry-sdk>=1.20.0",
+    "opentelemetry-api>=1.20.0",
 ]
 
 requires-python = ">= 3.12,<4"