Fix OSError: [Errno 24] Too many open files: 'nul' (#1455)

* Update model.py

Added closing of save_fds.

* Updated model.py for pre-commit requirements

Author: Sm1Ling

flaml/automl/model.py

@@ -2820,7 +2820,7 @@ def __init__(self):
         # Open a pair of null files
         self.null_fds = [os.open(os.devnull, os.O_RDWR) for x in range(2)]
         # Save the actual stdout (1) and stderr (2) file descriptors.
-        self.save_fds = (os.dup(1), os.dup(2))
+        self.save_fds = [os.dup(1), os.dup(2)]
 
     def __enter__(self):
         # Assign the null pointers to stdout and stderr.
@@ -2832,5 +2832,5 @@ def __exit__(self, *_):
         os.dup2(self.save_fds[0], 1)
         os.dup2(self.save_fds[1], 2)
         # Close the null files
-        os.close(self.null_fds[0])
-        os.close(self.null_fds[1])
+        for fd in self.null_fds + self.save_fds:
+            os.close(fd)