Use TextIOWrapper to typecheck scenario input

TextIOWrapper should be of type TextIO but TextIO does not seem to work
for typecheck. Just use the class as type argument of isinstance.

Author: sjmonson

src/guidellm/main.py

@@ -1,4 +1,5 @@
 import asyncio
+from io import TextIOWrapper
 from typing import Literal, Optional, Sequence, TextIO, Union, get_args
 
 import click
@@ -184,7 +185,7 @@ def generate_benchmark_report_cli(
 
     if isinstance(scenario, str):
         defaults = SCENARIOS[scenario]
-    elif isinstance(scenario, TextIO):
+    elif isinstance(scenario, TextIOWrapper):
         defaults = Scenario.from_json(scenario.read())
     elif scenario is None:
         defaults = Scenario()