ui: fix pyrefly str to LiteralString conversion error

Get rid of pyrefly error messages inside ui, caused by a type mismatch
between list[LiteralString] and the str type messages added to it.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>

Author: acerv

libkirk/ui.py

@@ -159,8 +159,9 @@ async def suite_completed(self, results: SuiteResults, exec_time: float) -> None
         duration = self._user_friendly_duration(results.exec_time)
         exec_time_uf = self._user_friendly_duration(exec_time)
 
-        message = []
+        message: list[str] = []
         message.append(" " * 128)
+
         message.append(f"Execution time: {exec_time_uf}\n")
         message.append(f"\tSuite:       {results.suite.name}")
         message.append(f"\tTotal runs:  {len(results.suite.tests)}")