Replace deprecated utcnow() with now(UTC) (#1097)

* Replace deprecated utcnow() with now(UTC)

* Update Python requirements

Author: hugovk

README.rst

@@ -24,8 +24,6 @@ The official home of this guide is https://devguide.python.org.
 Compilation
 -----------
 
-For the compilation of the devguide, you need to use a version of Python which
-supports the ``venv`` module, because the ``make html`` command will create a
-virtual environment and will install the ``Sphinx`` package::
+For the compilation of the devguide, Python 3.11+ is needed::
 
     make html

_tools/generate_release_cycle.py

@@ -44,7 +44,7 @@ def __init__(self) -> None:
 
     def write_csv(self) -> None:
         """Output CSV files."""
-        now_str = str(dt.datetime.utcnow())
+        now_str = str(dt.datetime.now(dt.UTC))
 
         versions_by_category = {"branches": {}, "end-of-life": {}}
         headers = None