Fix variable name typo

roles/custom/matrix-bot-maubot/tasks/setup_install.yml

@@ -53,7 +53,7 @@
     name: "{{ matrix_bot_maubot_docker_image }}"
     source: build
     force_source: "{{ matrix_bot_maubot_git_pull_results.changed if ansible_version.major > 2 or ansible_version.minor >= 8 else omit }}"
-    force: "{{ omit if ansible_version.major > 2 or ansible_version.minor >= 8 else matrix_mailer_git_pull_results.changed }}"
+    force: "{{ omit if ansible_version.major > 2 or ansible_version.minor >= 8 else matrix_bot_maubot_git_pull_results.changed }}"
     build:
       dockerfile: Dockerfile
       path: "{{ matrix_bot_maubot_docker_src_files_path }}"