🩹(summary) fix missing f-string

Spotted by code rabbit. Missing F-string was leading
to an unexpected behavior.

Author: lebaudantoine

src/summary/summary/core/llm_service.py

@@ -141,4 +141,4 @@ def call(
 
         except Exception as e:
             self._logger.exception("LLM call failed: %s", e)
-            raise LLMException("LLM call failed: {e}") from e
+            raise LLMException(f"LLM call failed: {e}") from e