Refs #15667 -- Prevented newlines in attrs.html widget rendering.

Removed the trailing newline from widget attrs.html template.
The solution may be revisited by fixing refs #9198 but not
for Django 1.11.

Thanks Dmitry Ivanchenko for the report and Preston Timmons for advice.

django/forms/templates/django/forms/widgets/attrs.html

@@ -1 +1 @@
-{% for name, value in widget.attrs.items %} {{ name }}{% if not value is True %}="{{ value }}"{% endif %}{% endfor %}
+{% for name, value in widget.attrs.items %} {{ name }}{% if not value is True %}="{{ value }}"{% endif %}{% endfor %}