fix(markdown): extra whitespace before and after pasted content #7364 (#7440)

* fix(markdown): extra whitespace before and after pasted content #7364

* fix(markdown): better solution for extra whitespace before and after pasted content #7364

---------

Co-authored-by: Yan <61414485+yanthomasdev@users.noreply.github.com>

Author: hip3r

packages/decap-cms-widget-markdown/src/MarkdownControl/plugins/html/withHtml.js

@@ -37,7 +37,7 @@ const INLINE_STYLES = {
 
 function deserialize(el) {
   if (el.nodeType === 3) {
-    return el.textContent;
+    return el.textContent.replace(/(\r)?\n/g, '');
   } else if (el.nodeType !== 1) {
     return null;
   } else if (el.nodeName === 'BR') {