Remove reference to missing csp_nonce variable

I don't think Airlock sends a CSP header so this isn't doing anything.
We can add this back as and when we need it.

Author: evansd

airlock/templates/base.html

@@ -12,7 +12,7 @@
 
     {% block extra_meta %}{% endblock %}
 
-    <script type="module" nonce="{{ request.csp_nonce }}">
+    <script type="module">
       document.documentElement.classList.remove("no-js");
       document.documentElement.classList.add("js");