Use block in file instead

arch-setup/install.yml

@@ -3,16 +3,12 @@
   become: yes
   tasks:
     - name: Enable multilib repository
-      ansible.builtin.lineinfile:
+      ansible.builtin.blockinfile:
         path: /etc/pacman.conf
-        search_string: "#[multilib]"
-        line: "[multilib]"
-
-    - name: Enable multilib repository (2)
-      ansible.builtin.lineinfile:
-        path: /etc/pacman.conf
-        search_string: "#Include = /etc/pacman.d/mirrorlist"
-        line: Include = /etc/pacman.d/mirrorlist
+        prepend_newline: true
+        block: |
+          [multilib]
+          Include = /etc/pacman.d/mirrorlist
 
     - name: Install official packages
       community.general.pacman: