Update pyenv to v2.6.20 to support Python 3.13.11 and 3.9.25

The autofix updated Python versions but pyenv v2.6.10 doesn't have
definitions for Python 3.13.11 and 3.9.25. Bump pyenv to v2.6.20.

Co-authored-by: Ona <no-reply@ona.com>

Author: kylos101

chunks/lang-python/Dockerfile

@@ -21,8 +21,8 @@ RUN sudo install-packages \
 	libncursesw5-dev xz-utils tk-dev libxml2-dev libxmlsec1-dev libffi-dev liblzma-dev \
 	# Install PYENV
 	&& git clone https://github.com/pyenv/pyenv.git ~/.pyenv \
-	# v2.6.10
-	&& git -C ~/.pyenv checkout a419b003b4615bef05098865bb97e0fbc428095e \
+	# v2.6.20
+	&& git -C ~/.pyenv checkout 3441980e83bb1c5fdb2f1734ae4dab694d10ef71 \
 	&& pyenv install ${PYTHON_VERSION} \
 	&& pyenv global ${PYTHON_VERSION} \
 	&& for exec in global; do printf '%s\n' 'source "$HOME/.gp_pyenv.d/userbase.bash"' >> "$PYENV_ROOT/libexec/pyenv-$exec"; done \