Radio: fix radio-button style when nested in a form-item

packages/theme-default/src/radio-group.css

@@ -6,6 +6,7 @@
     display: inline-block;
     font-size: 0;
     line-height: 1;
+    vertical-align: middle;
 
     & .el-radio {
       font-size: var(--radio-font-size);