Properly handle feed item creation date with surrounding whitespace

Some feeds might have whitespace around the creation date.
This can't be parsed by DateTimeFormat methods.
Therefore the incoming creation date is trimmed to not contain any
surrounding whitespace for proper handling.

Relates: #12686

src/Protocol/Feed.php

@@ -376,11 +376,11 @@ class Feed
 			}
 
 			if ($published != '') {
-				$item['created'] = $published;
+				$item['created'] = trim($published);
 			}
 
 			if ($updated != '') {
-				$item['edited'] = $updated;
+				$item['edited'] = trim($updated);
 			}
 
 			if (!$dryRun) {