fbcode_builder: recognize 'alma' as an rpm-using distro

Summary:
AlmaLinux is needed for PyPI generation.

AlmaLinux 8/9 reports its distro as "alma" via /etc/os-release. Without this entry in get_package_manager(), get_required_system_packages() returns no packages on Alma hosts and any [rpms.os=linux] manifest section is silently dropped, falling back to a from-source build that often fails (e.g. libaio).

Reviewed By: bigfootjon

Differential Revision: D104428963

fbshipit-source-id: 39d9fe1ec74c3276ccbcc9325778073f5a50bf53

Author: r-barnes

build/fbcode_builder/getdeps/platform.py

@@ -273,7 +273,7 @@ def get_package_manager(self) -> str | None:
             return None
         if self.is_darwin():
             return "homebrew"
-        if self.distro in ("fedora", "centos", "centos_stream", "rocky"):
+        if self.distro in ("fedora", "centos", "centos_stream", "rocky", "alma"):
             return "rpm"
         if self.distro is not None and self.distro.startswith(
             ("debian", "ubuntu", "pop!_os", "mint")