Bump gunicorn from 20.1.0 to 23.0.0

Dependabot couldn't find the original pull request head commit, 003b140.

Author: dependabot[bot]

requirements.txt

@@ -18,7 +18,7 @@ cssmin==0.2.0
 Cython==0.29.28
 extraction==0.3
 frozenlist==1.5.0
-gunicorn==20.1.0
+gunicorn==23.0.0
 hiredis==3.1.0
 html5lib==1.1
 httptools==0.6.4