Drop Ubuntu 18.04, 20.04, 22.04 and 24.04 support

[joachimmetz]

Various dependencies on Ubuntu 18.04, 20.04 and 22.04 lagging behind making maintenance time consuming. Drop Ubuntu 18.04, 20.04 and 22.04 support

• No support for pyproject.toml files
• Ubuntu 18.04 ships with Python 3.6 and that is blocking Python types adoption
• Ubuntu 20.04 ships with old gettext that is blocking libyal moving to a new version
• Ubuntu 22.04 ships with old version of setuptools
• Ubuntu 24.04 ships with old version of setuptools

autopoint: *** The AM_GNU_GETTEXT_VERSION declaration in your configure.ac
               file requires the infrastructure from gettext-0.21 but this version
               is older. Please upgrade to gettext-0.21 or newer.

• Remove from testing
  • Ubuntu 18.04
  • Ubuntu 20.04
  • Ubuntu 22.04
  • Ubuntu 24.04
• Remove from dev
  • Ubuntu 18.04
  • Ubuntu 20.04
  • Ubuntu 22.04
  • Ubuntu 24.04
• Remove from staging
  • Ubuntu 18.04
  • Ubuntu 20.04
  • Ubuntu 22.04
  • Ubuntu 24.04
• Remove from stable
  • Ubuntu 18.04
  • Ubuntu 20.04
  • Ubuntu 22.04
  • Ubuntu 24.04

[joachimmetz]

Ubuntu 18.04 builds removed from testing, dev and staging

[joachimmetz]

Ubuntu 20.04 builds removed from testing,

[joachimmetz]

Ubuntu 20.04 builds removed from dev and staging.

[joachimmetz]

Timesketch now on 24.04

[joachimmetz]

Ubuntu 22.04 builds removed from testing,

Ubuntu 26.04 coming next April

[joachimmetz]

Launchpad download stats indicate bionic is still being downloaded

python3-plaso_20220724-1ppa1~bionic 2025-10 210
python3-plaso_20220724-1ppa1~bionic 2025-11 30
python3-plaso_20220724-1ppa1~focal 2025-10 1190
python3-plaso_20220724-1ppa1~focal 2025-11 560
python3-plaso_20250918-1ppa1~noble 2025-10 7511
python3-plaso_20250918-1ppa1~noble 2025-11 8407