Use subprocess.DEVNULL for output redirection

xfel_calibrate/calibrate.py

@@ -11,7 +11,7 @@ from nbparameterise import (
 import os
 import pprint
 import re
-from subprocess import check_output
+from subprocess import check_output, DEVNULL
 import sys
 import warnings
 from .settings import *
@@ -163,11 +163,9 @@ def extract_title_author_version(nb):
     # in the _version.py file
     try:
         git_dir = os.path.join(PKG_DIR, '..', '.git')
-        FNULL = open(os.devnull, 'w')
-        version = check_output(['git',
-                                '--git-dir={}'.format(git_dir),
-                                'describe', '--tag'],
-                               stderr=FNULL).decode('utf8')
+        version = check_output([
+            'git', f'--git-dir={git_dir}', 'describe', '--tag',
+        ], stderr=DEVNULL).decode('utf8')
         version = version.replace("\n", "")
     except:
         from .VERSION import __version__