modify gunicorn requirment.txt

requirements.txt

@@ -25,4 +25,4 @@ pandas ; python_version >= "3"
 pandas < 0.25.0 ; python_version < "3"
 
 # gunicorn not support windows
-gunicorn >= 19.10.0; sys_platform == "darwin" or sys_platform == "linux"
+gunicorn >= 19.10.0; sys_platform != "win32"