I wanted to install python 3.10 but that version is not available on pyenv version list.
checked by pyenv install --list.
People suggested to upgrade pyenv that but I do not see help related to updating pyenv.
pyenv isn't really 'installed' in a traditional sense, it's just a git checkout. All you have to do to update is
cd ~/.pyenv
git pull
That also updates the list of available python versions.