Remove support for Ubuntu 20.04 and Debian 11.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

scripts/lib/install

@@ -231,15 +231,13 @@ if [ -f /etc/os-release ]; then
 fi
 
 case "$os_id $os_version_id" in
-    'debian 11' | 'debian 12' | 'ubuntu 20.04' | 'ubuntu 22.04' | 'ubuntu 24.04') ;;
+    'debian 12' | 'ubuntu 22.04' | 'ubuntu 24.04') ;;
     *)
         system_requirements_failure <<EOF
 Unsupported OS release: $os_id $os_version_id
 
 Zulip in production is supported only on:
- - Debian 11
  - Debian 12
- - Ubuntu 20.04 LTS
  - Ubuntu 22.04 LTS
  - Ubuntu 24.04 LTS
 EOF

scripts/lib/puppet_cache.py

@@ -8,7 +8,7 @@ from urllib.request import urlopen
 
 import yaml
 
-from .zulip_tools import parse_os_release, run
+from .zulip_tools import run
 
 ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 ZULIP_SRV_PATH = "/srv"
@@ -89,11 +89,6 @@ def install_puppet_module(
             tarball.write(tarball_content)
             tarball.flush()
 
-        # This is to suppress Puppet warnings with ruby 2.7.
-        distro_info = parse_os_release()
-        puppet_env = os.environ.copy()
-        if (distro_info["ID"], distro_info["VERSION_ID"]) in [("ubuntu", "20.04")]:
-            puppet_env["RUBYOPT"] = "-W0"
         run(
             [
                 "puppet",
@@ -104,5 +99,4 @@ def install_puppet_module(
                 tarball.name,
                 "--ignore-dependencies",
             ],
-            env=puppet_env,
         )

scripts/lib/upgrade-zulip-from-git

@@ -112,7 +112,7 @@ try:
         ).splitlines()
 
         # We can't use `git worktree list --porcelain -z` here because
-        # Ubuntu 20.04 Focal only has git 2.25.1, and -z was
+        # Ubuntu 22.04 only has git 2.34.1, and -z was
         # introduced in 2.36
         worktree_data = subprocess.check_output(
             ["git", "worktree", "list", "--porcelain"],