Update var reference

ansible/roles/metacluster/tasks/k3s.yml

@@ -8,7 +8,7 @@
 
 - name: Download & install K3s binary
   ansible.builtin.get_url:
-    url: https://github.com/k3s-io/k3s/releases/download/{{ k3s.version }}/k3s
+    url: https://github.com/k3s-io/k3s/releases/download/{{ platform.k3s.version }}/k3s
     dest: /usr/local/bin/k3s
     owner: root
     group: root
@@ -16,7 +16,7 @@
 
 - name: Download K3s images tarball
   ansible.builtin.get_url:
-    url: https://github.com/k3s-io/k3s/releases/download/{{ k3s.version }}/k3s-airgap-images-amd64.tar.gz
+    url: https://github.com/k3s-io/k3s/releases/download/{{ platform.k3s.version }}/k3s-airgap-images-amd64.tar.gz
     dest: /var/lib/rancher/k3s/agent/images
 
 - name: Download K3s install script