Add OS variant configuration

- Debian 11 has a different TFTP path than Ubuntu 18.04

Add EFI PXE boot support with conditional

- Conditionally provide different file depending on BIOS or EFI boot
  (unsupported on BSD dhcpd implementations)

Fix galaxy metadata

Change-Id: If13d18dbf0455f8e9b27054da6f0eabbb602b71f
diff --git a/tasks/main.yml b/tasks/main.yml
index 80927ec..c33ddc4 100644
--- a/tasks/main.yml
+++ b/tasks/main.yml
@@ -5,7 +5,11 @@
 # SPDX-License-Identifier: Apache-2.0
 
 - name: include OS-specific vars
-  include_vars: "{{ ansible_os_family }}.yml"
+  include_vars: "{{ item }}"
+  with_first_found:
+    - "{{ ansible_distribution }}_{{ ansible_distribution_version }}.yml"
+    - "{{ ansible_distribution }}.yml"
+    - "{{ ansible_os_family }}.yml"
 
 - name: include OS-specific tasks
   include_tasks: "{{ ansible_os_family }}.yml"