drop ubuntu focal from CI (#13021)

* drop ubuntu focal from CI

its EOL

* Update installation.rst

Author: alex

.github/workflows/ci.yml

@@ -160,7 +160,6 @@ jobs:
           - {IMAGE: "bookworm", NOXSESSION: "tests", RUNNER: "ubuntu-latest"}
           - {IMAGE: "trixie", NOXSESSION: "tests", RUNNER: "ubuntu-latest"}
           - {IMAGE: "sid", NOXSESSION: "tests", RUNNER: "ubuntu-latest"}
-          - {IMAGE: "ubuntu-focal", NOXSESSION: "tests", RUNNER: "ubuntu-latest"}
           - {IMAGE: "ubuntu-jammy", NOXSESSION: "tests", RUNNER: "ubuntu-latest"}
           - {IMAGE: "ubuntu-noble", NOXSESSION: "tests", RUNNER: "ubuntu-latest"}
           - {IMAGE: "ubuntu-rolling", NOXSESSION: "tests", RUNNER: "ubuntu-latest"}

docs/installation.rst

@@ -28,7 +28,7 @@ operating systems.
 * x86-64 CentOS Stream 9, 10
 * x86-64 Fedora (latest)
 * x86-64 macOS 13 Ventura and ARM64 macOS 14 Sonoma
-* x86-64 Ubuntu 20.04, 22.04, 24.04, rolling
+* x86-64 Ubuntu 22.04, 24.04, rolling
 * ARM64 Ubuntu rolling
 * ARMv7l Ubuntu rolling
 * x86-64 Debian Bullseye (11.x), Bookworm (12.x), Trixie (13.x), and