Seems like the back branches are still not quite there: I'm seeing
Name "PostgreSQL::Test::Utils::windows_os" used only once: possible typo at t/003_extrafiles.pl line 74.
in v12 and v13, while it's
Name "PostgreSQL::Test::Utils::windows_os" used only once: possible typo at t/003_extrafiles.pl line 85.
in v14. v15 and up are OK.
regards, tom lane