refactor: improve styles for the git branch button in git panel toolbar

Author: devvaannsh

src/extensions/default/Git/styles/git-styles.less

@@ -1116,14 +1116,15 @@
         box-sizing: border-box;
         height: 22px;
         margin-top: 2px;
-        margin-right: 8px;
+        margin-right: 4px;
         padding: 2px 10px;
         font-size: 12px;
         line-height: 16px;
         white-space: nowrap;
         cursor: default;
         i {
             margin-right: 4px;
+            font-size: 10px;
         }
         &:not(.clickable) {
             opacity: .5;