Bump grpcio in /docs/examples/fork-process-model/flask-gunicorn (#4092)

Author: dependabot[bot]

docs/examples/fork-process-model/flask-gunicorn/requirements.txt

@@ -1,7 +1,7 @@
 click==8.1.7
 Flask==2.3.3
 googleapis-common-protos==1.52.0
-grpcio==1.56.0
+grpcio==1.56.2
 gunicorn==22.0.0
 itsdangerous==2.1.2
 Jinja2==3.1.4