Bump gunicorn from 21.2.0 to 22.0.0 in /backend (#1176)

Bumps [gunicorn](https://github.com/benoitc/gunicorn) from 21.2.0 to 22.0.0.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](https://github.com/benoitc/gunicorn/compare/21.2.0...22.0.0)

---
updated-dependencies:
- dependency-name: gunicorn
  dependency-type: direct:production
...

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backend/poetry.lock

@@ -667,22 +667,23 @@ test = ["objgraph", "psutil"]
 
 [[package]]
 name = "gunicorn"
-version = "21.2.0"
+version = "22.0.0"
 description = "WSGI HTTP Server for UNIX"
 optional = false
-python-versions = ">=3.5"
+python-versions = ">=3.7"
 files = [
-    {file = "gunicorn-21.2.0-py3-none-any.whl", hash = "sha256:3213aa5e8c24949e792bcacfc176fef362e7aac80b76c56f6b5122bf350722f0"},
-    {file = "gunicorn-21.2.0.tar.gz", hash = "sha256:88ec8bff1d634f98e61b9f65bc4bf3cd918a90806c6f5c48bc5603849ec81033"},
+    {file = "gunicorn-22.0.0-py3-none-any.whl", hash = "sha256:350679f91b24062c86e386e198a15438d53a7a8207235a78ba1b53df4c4378d9"},
+    {file = "gunicorn-22.0.0.tar.gz", hash = "sha256:4a0b436239ff76fb33f11c07a16482c521a7e09c1ce3cc293c2330afe01bec63"},
 ]
 
 [package.dependencies]
 packaging = "*"
 
 [package.extras]
-eventlet = ["eventlet (>=0.24.1)"]
+eventlet = ["eventlet (>=0.24.1,!=0.36.0)"]
 gevent = ["gevent (>=1.4.0)"]
 setproctitle = ["setproctitle"]
+testing = ["coverage", "eventlet", "gevent", "pytest", "pytest-cov"]
 tornado = ["tornado (>=0.2)"]
 
 [[package]]
@@ -2216,4 +2217,4 @@ files = [
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.10"
-content-hash = "fcb0885e9c828f562a30c2690166bd1f41ce591779bb13deaaf6925463a53dda"
+content-hash = "2b39e4adc3855245be1eb5ce1d9e98ce382b907ddb0f98922168312b52a77b1e"