Add variable-deprecation task for Buscarron

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3157

roles/custom/matrix-bot-buscarron/tasks/validate_config.yml

@@ -1,4 +1,15 @@
 ---
+- name: (Deprecation) Catch and report renamed Buscarron settings
+  ansible.builtin.fail:
+    msg: >-
+      Your configuration contains a variable, which now has a different name.
+      Please change your configuration to rename the variable (`{{ item.old }}` -> `{{ item.new }}`).
+  when: "item.old in vars"
+  with_items:
+    - {'old': 'matrix_bot_buscarron_noencryption', 'new': '<removed>'}
+    - {'old': 'matrix_bot_buscarron_spam_hosts', 'new': '<superseded by matrix_bot_buscarron_spamlist>'}
+    - {'old': 'matrix_bot_buscarron_spam_emails', 'new': '<superseded by matrix_bot_buscarron_spamlist>'}
+    - {'old': 'matrix_bot_buscarron_spam_localparts', 'new': '<superseded by matrix_bot_buscarron_spamlist>'}
 
 - name: Fail if required Buscarron settings not defined
   ansible.builtin.fail: