Fix button hover border (#30048)

Fix regression from https://github.com/go-gitea/gitea/pull/30014. The
rule was to broad and affecting things like `primary` button
unintentionally.

web_src/css/modules/button.css

@@ -11,7 +11,6 @@
 .ui.button:hover {
   background: var(--color-hover);
   color: var(--color-text);
-  border-color: var(--color-secondary-dark-2);
 }
 
 .page-content .ui.button {
@@ -62,6 +61,10 @@ It needs some tricks to tweak the left/right borders with active state */
   border-right: none;
 }
 
+.ui.buttons .button:hover {
+  border-color: var(--color-secondary-dark-2);
+}
+
 .ui.buttons .button:hover + .button {
   border-left: 1px solid var(--color-secondary-dark-2);
 }