Remove dashes between organization member avatars on hover (#23034)

On the home page of an organization, there are unexpected dashes between
the avatars of the members when hovering over the avatars, as shown in
below:

![hover including title](https://user-images.githubusercontent.com/17645053/220271470-4f49e16f-87eb-4ffa-b38e-23feae1ff92d.png)

![hover without title](https://user-images.githubusercontent.com/17645053/220271512-e4a67685-6b72-4742-a34f-e01ed248c1de.png)

This is because in `fomantic/build/semantic.css` there is a
rule `text-decoration: underline;` when hovering over the `<a>` tag.
Here, the `<a>` tag has width and height because of the avatar image inside,
leading to the unexpected underlines.

This PR overrides the `a:hover` rule so the underline does not exist anymore.

Co-authored-by: delvh <leon@kske.dev>

web_src/less/_organization.less

@@ -93,6 +93,10 @@
   &.teams,
   &.profile {
     .members {
+      a:hover {
+        text-decoration: none;
+      }
+
       .ui.avatar {
         width: 48px;
         height: 48px;