You release is so old and unsupported since 2019, that the official docs don't even mention the available Python packages for Version 12: Available Python versions - Ubuntu for Developers

Python 3 was added to Ubuntu only at version 14.10 - Python/3 - Ubuntu Wiki

Is there a good reason to remain on that version, considering hundreds of exploitable security vulnerabilites - Canonical Ubuntu Linux 12.04 security vulnerabilities, CVEs?