Fix typo

roles/float-infra-prometheus/templates/prometheus.yml.j2

@@ -215,7 +215,7 @@ scrape_configs:
  # - caller provides a list of hosts, or a float service
  # - caller provides a regexp to turn the hosts into targets
  #}
-{% set custom_blackbox_targets = p.targets if p.targets is defined else groups[p.get('target_service, 'frontend')] %}
+{% set custom_blackbox_targets = p.targets if p.targets is defined else groups[p.get('target_service', 'frontend')] %}
 {% for target in custom_blackbox_targets %}
           - "{{ target | regex_replace('^(.*)$', p.target_regex | default('\\1')) }}"
 {% endfor %}