chore(deps): update dependency gunicorn to v25

Author: renovate[bot]

setup.py

@@ -11,7 +11,7 @@
 README = open(os.path.join(here, 'README.rst')).read()
 
 install_requires = ['Flask', 'flask-cors', 'guessit>=3.7.1',
-                    'flask-restful>=0.3.6', 'gunicorn==20.1.0']
+                    'flask-restful>=0.3.6', 'gunicorn==25.3.0']
 
 setup_requires = ['pytest-runner']