fix: prevent OntoGPT cache-related errors by clearing cache

Implement a cache-clearing mechanism before each OntoGPT call to
mitigate issues where cached results, particularly those without
grounded concepts, could lead to processing errors. This ensures that
each call to OntoGPT is fresh and produces reliable results.

src/spinneret/annotator.py

@@ -680,6 +680,9 @@ def get_ontogpt_annotation(
         if local_model is not None:
             cmd += f"  -m ollama/{local_model}"
         try:
+            # Clear the cache so that the model can derive new annotations
+            cache_path = os.getcwd() + "/.litellm_cache"
+            os.system(f"rm -rf {cache_path}")
             os.system(cmd)
         except Exception as e:  # pylint: disable=broad-exception-caught
             print(f"Error calling OntoGPT: {e}")