Fix copy-paste error message in OpenTelemetryPlugin (#1649)

The no-runner guard named the OpenAI plugin, a copy-paste leftover from
the OpenAI-agents plugin.

Author: xumaple

temporalio/contrib/opentelemetry/_plugin.py

@@ -34,7 +34,9 @@ def __init__(self, *, add_temporal_spans: bool = False):
 
         def workflow_runner(runner: WorkflowRunner | None) -> WorkflowRunner:
             if not runner:
-                raise ValueError("No WorkflowRunner provided to the OpenAI plugin.")
+                raise ValueError(
+                    "No WorkflowRunner provided to the OpenTelemetry plugin."
+                )
 
             # If in sandbox, add additional passthrough
             if isinstance(runner, SandboxedWorkflowRunner):