always trim editableText from itemBox on blur (#5081)

So that whitespaces are removed even if the itemBox
does not refresh.

Fixes: #5080

chrome/content/zotero/elements/itemBox.js

@@ -2198,6 +2198,8 @@
 				textbox.setAttribute("min-lines", 1);
 			}
 			var value = textbox.value.trim();
+			// Remove trailing whitespaces from editable-text in case itemBox is not refreshed
+			textbox.value = value;
 			
 			var [field, creatorIndex, creatorField] = fieldName.split('-');