Fix tmux config being added multiple times

tasks/main.yml

@@ -11,10 +11,10 @@
     owner: "{{ ansible_user }}"
     mode: "0644"
 
-- name: Use tmux as default shell and attach to existing session
+- name: Ensure tmux is used as default shell
-  ansible.builtin.lineinfile:
+  ansible.builtin.blockinfile:
     path: /root/.bashrc
-    line: |
+    block: |
       case $- in
         *i*) 
           if command -v tmux &>/dev/null; then
@@ -24,3 +24,4 @@
           fi
           ;;
       esac
+    marker: "# {mark} ANSIBLE TMUX CONFIG"