chore: update pyenv and default python version. (#1335)

Author: feanil

changelog.d/20260121_123520_feanil_patch_2.md

@@ -0,0 +1,13 @@
+<!--
+Create a changelog entry for every new user-facing change. Please respect the following instructions:
+- Indicate breaking changes by prepending an explosion 💥 character.
+- Prefix your changes with either [Bugfix], [Improvement], [Feature], [Security], [Deprecation].
+- You may optionally append "(by @<author>)" at the end of the line, where "<author>" is either one (just one)
+  of your GitHub username, real name or affiliated organization. These affiliations will be displayed in
+  the release notes for every release.
+-->
+
+<!-- - 💥[Feature] Foobarize the blorginator. This breaks plugins by renaming the `FOO_DO` filter to `BAR_DO`. (by @regisb) -->
+<!-- - [Improvement] This is a non-breaking change. Life is good. (by @billgates) -->
+
+[Improvement] Update to use Python 3.12 for edx-platform

tutor/templates/build/openedx/Dockerfile

@@ -29,9 +29,9 @@ RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
 # Install pyenv
 # https://www.python.org/downloads/
 # https://github.com/pyenv/pyenv/releases
-ARG PYTHON_VERSION=3.11.8
+ARG PYTHON_VERSION=3.12.12
 ENV PYENV_ROOT=/opt/pyenv
-RUN git clone https://github.com/pyenv/pyenv $PYENV_ROOT --branch v2.3.36 --depth 1
+RUN git clone https://github.com/pyenv/pyenv $PYENV_ROOT --branch v2.6.18 --depth 1
 
 # Install Python
 RUN $PYENV_ROOT/bin/pyenv install $PYTHON_VERSION