install_arch: verify bootstrap image signature

Fixes #458 (closed).

roles/install_arch/tasks/main.yml

@@ -42,15 +42,12 @@
 
 - name: Download bootstrap image
   get_url:
-    url: https://geo.mirror.pkgbuild.com/iso/{{ bootstrap_version }}/archlinux-bootstrap-x86_64.tar.gz
-    dest: /tmp/
-    mode: 0644
-
-- name: Download bootstrap signature
-  get_url:
-    url: https://geo.mirror.pkgbuild.com/iso/{{ bootstrap_version }}/archlinux-bootstrap-x86_64.tar.gz.sig
+    url: {{ item }}
     dest: /tmp/
     mode: 0644
+  loop:
+    - https://geo.mirror.pkgbuild.com/iso/{{ bootstrap_version }}/archlinux-bootstrap-x86_64.tar.gz
+    - https://geo.mirror.pkgbuild.com/iso/{{ bootstrap_version }}/archlinux-bootstrap-x86_64.tar.gz.sig
 
 - name: Get pierre's key
   ansible.builtin.command: gpg --locate-keys pierre@archlinux.de