theme-default: fix form-item label-top style

use `text-align: left` to display line-wrapped labels properly

packages/theme-default/src/form.css

@@ -12,6 +12,7 @@
       & .el-form-item__label {
         float: none;
         display: inline-block;
+        text-align: left;
         padding: 0 0 10px 0;
       }
     }