Add a border around season’s color icon

This is because the public design, not yet implemented here, does it
too.

web/templates/admin/season/index.gohtml

@@ -25,7 +25,7 @@
                     <td><a href="/admin/seasons/{{ .Slug }}">{{ .Name }}</a></td>
                     <td>
                         <svg width="20px" height="20px">
-                            <circle cx="50%" cy="50%" r="50%" fill="{{ .Color }}"/>
+                            <circle cx="50%" cy="50%" r="49%" fill="{{ .Color }}" stroke="#000" stroke-width=".5"/>
                         </svg>
                     </td>
                     <td>{{ if .Active }}{{( gettext "Yes" )}}{{ else }}{{( gettext "No" )}}{{ end }}</td>