fix: line-height set to 1 on uui-button (#1114)

Using line-height: 1; insted of line-height: normal; in .label css class style fixes vertical alignment ensuring the line height to exactly 1 times the font size. Ensures consistent spacing across different fonts and browsers.

Author: alevak09

packages/uui-button/lib/uui-button.element.ts

@@ -292,7 +292,7 @@ export class UUIButtonElement extends UUIFormControlMixin(
       }
 
       .label {
-        line-height: normal; /** needed to reset 'a > span' */
+        line-height: 1; /** needed to reset 'a > span' */
         transition: opacity 120ms;
         display: flex;
         gap: var(--uui-size-1);