fix: block not work when small size (ant-design#33878)

tangjinzhou · Amour1688 · commit d466f4766f30 · 2022-01-30T14:00:51.000+08:00
vueComponent/ant-design-vue#5219
diff --git a/components/button/style/index.less b/components/button/style/index.less
@@ -256,7 +256,7 @@
     letter-spacing: 0.34em;
   }
 
-  &-block {
+  &&-block {
     width: 100%;
   }
 
