Install cargo only if pkg_cargo needs it

tasks/pkgs/rust.yml

@@ -1,17 +1,10 @@
 # vim: set filetype=yaml.ansible :
 ---
-- name: Add rust
-  when:
-    - rust_configured is undefined
-  block:
-    - name: Load rust config
-      ansible.builtin.include_tasks:
-        file: config/rust.yml
+- name: Load rust config
+  ansible.builtin.include_tasks:
+    file: config/rust.yml
 
-    - name: Append rust to pkgs
-      ansible.builtin.set_fact:
-        pkg_sys: "{{ pkg_sys + rust.pkgs }}"
-
-    - name: Set rust_configured
-      ansible.builtin.set_fact:
-        rust_configured: true
+- name: Install rust and cargo
+  become: true
+  ansible.builtin.package:
+    name: "{{ rust.pkgs }}"