chore(deps): update dependency gunicorn to v21

cc671045 · Renovate Bot · 56228b82 · cc671045
Commit cc671045 authored Jul 24, 2023 by Renovate Bot
--- a/requirements.txt
+++ b/requirements.txt
 Django==4.2.1
 whitenoise==6.5.0
-gunicorn==20.1.0
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+gunicorn==21.2.0
\ No newline at end of file