fix(efi): collapse fmask/dmask dedup to dict.fromkeys one-liner

Per @Torxed's review feedback. Same semantics as the previous loop
(dedupe by exact-string match) but shorter. dict.fromkeys preserves
insertion order, where set() would not.

archinstall/lib/installer.py

@@ -378,9 +378,7 @@ class Installer:
 			options = list(part_mod.mount_options)
 
 			if part_mod.is_efi():
-				for opt in ('fmask=0077', 'dmask=0077'):
-					if opt not in options:
-						options.append(opt)
+				options = list(dict.fromkeys(options + ['fmask=0077', 'dmask=0077']))
 
 			mount(part_mod.dev_path, target, options=options)
 		elif part_mod.fs_type == FilesystemType.BTRFS: