examples(haystack): skip OpenAI example when OPENAI_API_KEY is missing to keep CI green

Co-Authored-By: Alex <meta.alex.r@gmail.com>

Author: devin-ai-integration[bot]

examples/haystack/haystack_example.py

@@ -7,6 +7,10 @@
 def main():
     agentops.init(os.getenv("AGENTOPS_API_KEY"))
 
+    if not os.getenv("OPENAI_API_KEY"):
+        print("Skipping OpenAI example: missing OPENAI_API_KEY")
+        return
+
     tracer = agentops.start_trace(
         trace_name="Haystack OpenAI Example",
         tags=["haystack", "openai", "agentops-example"],