fix tps loader - OutputOnly submission format

changed to par with https://github.com/cms-dev/cms/blob/293c52769cb71060ceef951ac9b40dca35a901e5/cms/grading/tasktypes/OutputOnly.py#L55C5-L55C35

Author: AlirezaKeshavarz83

cmscontrib/loaders/tps.py

@@ -184,7 +184,7 @@ def get_task(self, get_statement=True):
         if data["task_type"] == 'OutputOnly':
             args["submission_format"] = list()
             for codename in testcase_codenames:
-                args["submission_format"].append("%s.out" % codename)
+                args["submission_format"].append("output_%s.txt" % codename)
         elif data["task_type"] == 'Notice':
             args["submission_format"] = list()
         else: