Fix excess whitespace around group_linked macro

Previously this would add whitespace before/after any time this was
called, which isn't always wanted.

tildes/tildes/templates/macros/links.jinja2

@@ -5,6 +5,6 @@
   <a href="/user/{{ username }}" class="link-user">{{ username }}</a>
 {%- endmacro %}
 
-{% macro group_linked(group_path) %}
+{% macro group_linked(group_path) -%}
   <a href="/~{{ group_path }}" class="link-group">~{{ group_path }}</a>
-{% endmacro %}
+{%- endmacro %}