[FIX] website_blog: prevent the use of blog sidebar select

Before this commit, the user could use the blog publication date
selector situated in the blog sidebar even when he was in edit mode.
This date selector should behave like a link, it should not work in edit
mode. This commit prevents the user from using this selector while he is
in edit mode.

Steps to reproduce the bug:
- Go to /blog
- Edit the page
- Enable the sidebar option
- Click on the select in the sidebar
- Click on a date

=> An error is displayed.

task-3213851

closes odoo/odoo#121142

X-original-commit: 7e8e12c40b03d923b17831d95a5fe94410c2a56e
Signed-off-by: Outagant Mehdi (mou) <mou@odoo.com>
Signed-off-by: Dieleman Guillaume <gdi@odoo.com>

addons/website_blog/static/src/scss/website_blog.scss

@@ -277,6 +277,11 @@ $o-wblog-loader-size: 50px;
         #o_wblog_sidebar .oe_structure:empty {
             display: none;
         }
+
+        // Prevent users from using the select in the sidebar during edit.
+        .o_wblog_sidebar_block select[name="archive"] {
+            pointer-events: none;
+        }
     }
 }