feat(pr review): add more space on mobile (#21326)

This PR adds more space to the review screen on mobile so that comments
are more readable and less "squashed" an smaller screens.

Before:

![Screen Shot 2022-10-03 at 17 12
26](https://user-images.githubusercontent.com/13721712/193612834-6add9e25-f635-4a5b-84f6-b8e2b320ec29.png)

After:

![Screen Shot 2022-10-03 at 17 10
15](https://user-images.githubusercontent.com/13721712/193612671-ab4ef640-0360-44ef-9184-b366b7abeb37.png)

Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: Lauris BH <lauris@nix.lv>

web_src/less/_repository.less

@@ -988,6 +988,12 @@
         .comment-form-reply .footer {
           padding-bottom: 1em;
         }
+
+        @media @mediaSm {
+          .ui.segments {
+            margin-left: -2rem;
+          }
+        }
       }
 
       .ui.comments {
@@ -1165,6 +1171,10 @@
           box-shadow: none;
         }
       }
+
+      @media @mediaSm {
+        padding: 1rem 0 !important; // Important is required here to override existing fomantic styles.
+      }
     }
 
     .ui.depending {