fix(master): master.d template to support saltclass ext_pillar

salt/files/master.d/f_defaults.conf

@@ -1207,12 +1207,16 @@ ext_pillar:
       {%- for parameter in pillar[key] %}
         {%- if parameter is iterable and parameter is not string %}
         {%- for param, children in parameter.items() %}
+          {%- if children is string %}
+    - {{ param }}: {{ children }}
+          {%- else %}
     - {{ param }}:
           {%- for child in children %}
             {%- for key, value in child.items() %}
       - {{ key }}: {{ value }}
             {%- endfor -%}
           {%- endfor -%}
+          {%- endif -%}
         {%- endfor -%}
         {%- else %}
     - {{ parameter }}