Update install_runner_unix.yml

Resolves the following error due to how `ansible_distribution` resolves for macOS distributions
```
TASK [monolithprojects.github_actions_runner : STOP and disable Github Actions Runner service] ****************************
fatal: [build-agent-26]: FAILED! => {"changed": true, "cmd": ["./svc.sh", "stop"], "delta": "0:00:00.004103", "end": "2024-11-04 15:02:53.034496", "msg": "non-zero return code", "rc": 1, "start": "2024-11-04 15:02:53.030393", "stderr": "", "stderr_lines": [], "stdout": "Must not run with sudo", "stdout_lines": ["Must not run with sudo"]}
```

Author: dgilbert-foreflight

tasks/install_runner_unix.yml

@@ -165,7 +165,7 @@
   args:
     chdir: "{{ runner_dir }}"
   changed_when: true
-  become: "{{ 'false' if ansible_distribution == 'MacOS' else 'true' }}"
+  become: "{{ 'false' if ansible_distribution == 'MacOSX' else 'true' }}"
   no_log: "{{ hide_sensitive_logs | bool }}"
   ignore_errors: "{{ ansible_check_mode }}"
   when: runner_state|lower == "stopped"