Fix repository URL field name in project submissions template

Co-authored-by: alexeygrigorev <875246+alexeygrigorev@users.noreply.github.com>

Author: Copilot

cadmin/templates/cadmin/project_submissions.html

@@ -86,8 +86,8 @@ <h2>{{ project.title }} - Submissions</h2>
           {% endif %}
         </td>
         <td>
-          {% if submission.repository_url %}
-            <a href="{{ submission.repository_url }}" target="_blank">View</a>
+          {% if submission.github_link %}
+            <a href="{{ submission.github_link }}" target="_blank">View</a>
           {% else %}
             -
           {% endif %}